Total guess but was the CAB created on a MOSS farm and being deployed on
a WSS only farm?

Yes CAB was created in MOSS farm and also deployed in MOSS farm...
However, I am not pretty much clear on your question.

Actually PremiumRootSite/feature.xml folder  is missing from
12/Template folder structure, I suppose, b'coz of this it is unable
to pick up the import  command, can you help  me out to get this XML
file and how does it come, is it during installation  or any thing
else?

Is PremiumRootSite/feature.xml in the source MOSS farm? If not, it
shouldn't be working there either.

The next step would be to see the contents of the Manifest.xml file  from
within the CAB. Can you copy out that xml  and send it to me as text?

PremiumRootSite/feature.xml in the source MOSS farm is present.

Manifest's file  size is too large to attach...
I am pasting a part of it....Please go through it and let me know if you can
find some...

<?xml version="1.0" encoding="utf-8"?>
<SPObjects xmlns="urn:deployment-manifest-schema">
<SPObject Id="63dbe19a-ba22-4c04-a537-5d8edf7eaa72" ObjectType="SPSite"
ParentId="" ParentWebId="">
<Site Id="63dbe19a-ba22-4c04-a537-5d8edf7eaa72" />
</SPObject>
<SPObject Id="196a016e-93d7-4096-9173-a5794ec84996" ObjectType="SPWeb"
ParentId="" ParentWebId="196a016e-93d7-4096-9173-a5794ec84996" ParentWebUrl="/"
Url="/">
<Web Id="196a016e-93d7-4096-9173-a5794ec84996" Name="" Description="This
is the EuCan CoEx Test site for MOSS 2007" Locale="English (United States)"
CurrencyLocaleId="1033" Language="1033" TimeZoneId="3" Time24="false"
CalendarType="1" AdjustHijriDays="0" Collation="25"
RegionalSettingsLocaleId="1033" AlternateCalendarType="0" ShowWeeks="false"
FirstWeekOfYear="0" WorkDays="62" WorkDayStartHour="480" WorkDayEndHour="1020"
FirstDayOfWeek="0" Configuration="0" PresenceEnabled="true"
SyndicationEnabled="true" QuickLaunchEnabled="true" TreeViewEnabled="false"
ParserEnabled="true" Provisioned="true"
ParentId="00000000-0000-0000-0000-000000000000" IsRootWeb="true" Title="Home"
ServerRelativeUrl="/" WebTemplate="SPS" AlternateCssUrl="" CustomizedCssFiles=""
CustomJSUrl="" IncludeSupportingFolders="false"
RootFolderId="356ced22-180a-42f7-8f03-b0947fd38a09"
SystemCatalogsIncluded="true" ThemeComposite=""
SecurityProvider="00000000-0000-0000-0000-000000000000"
MasterUrl="/_catalogs/masterpage/custom.master"
CustomMasterUrl="/_catalogs/masterpage/custom.master"
Created="2006-07-10T11:28:43Z" Author="1"
SiteLogoUrl="/_layouts/images/titlegraphic.jpg" SiteLogoDescription="">
<Properties>
<Property Name="__SiteColDocumentsListId" Type="String"
Access="ReadWrite" Value="d730ebbe-aff3-46d8-9f2a-a8e2ae6825a6" />
<Property Name="NavigationProperiesSet" Type="String"
Access="ReadWrite" Value="True" />
<Property Name="__InheritsCustomMasterUrl" Type="String"
Access="ReadWrite" Value="False" />
<Property Name="vti_usagedownload" Type="String"
Access="ReadWrite" Value="131 19025 23770 68416 65706 61175 52085 20152 0 47347"
/>
<Property Name="__IncludePagesInNavigation" Type="String"
Access="ReadWrite" Value="False" />
<Property Name="__DocumentsListId" Type="String"
Access="ReadWrite" Value="031b48dc-8a55-4de5-90d1-a4bffa339d1f" />
<Property Name="DefaultSiteDirectorySiteId" Type="String"
Access="ReadWrite" Value="63dbe19a-ba22-4c04-a537-5d8edf7eaa72" />
<Property Name="__PagesListName" Type="String"
Access="ReadWrite" Value="Pages" />
<Property Name="vti_usagevisitsbyday" Type="String"
Access="ReadWrite" Value="1 5 1 0 0 0 1 0 0 0 0 0 1 3 1 0 1 0 0 104 38 96 150
198 139 144 216 73 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 104 116 0 0 0 186
169 84 0 165 156 194 17 143 72 138 77 139 76 153 56 128 85 138 153 170 170 78
200 144 167 120 65 141 78 2 164 45 142 165 166 151 80 161 53 136 155 167 33 138
80 110 166 13 137 148 165 46 159 136 174 98 145 159 168 45 131 88 167 145 160 29
127 45 0 0 0 133 92 158 131 160 133 160 80 160 146 160 129 164 39 117 160 61 130
161 145 138 144 161 84 156 161 157 160 138 169 145 157 89 139 85 201 59 121 131
157 106 158 108 129 175 99 157 138 165 140 154 0 0 21 11 1 1 1 0 0 2 22 7 18 43
0 0 5 8 1 6 0 257 251 256 61 172 11 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 162 207 696 837
259 204 462" />
<Property Name="quickdeployjobs" Type="String"
Access="ReadWrite" Value="<?xml version="1.0"
encoding="utf-16"?><ArrayOfGuid
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:xsd="http://www.w3.org/2001/XMLSchema" />" />
<Property Name="vti_runfullrecalc" Type="Integer"
Access="ReadWrite" Value="1" />
<Property Name="__PagesListId" Type="String" Access="ReadWrite"
Value="14c3e036-f3e2-46c5-b4df-ee5b1970665f" />
<Property Name="vti_siteusagetotalbandwidth" Type="Integer"
Access="ReadWrite" Value="46389" />
<Property Name="__InheritsMasterUrl" Type="String"
Access="ReadWrite" Value="False" />
<Property Name="vti_categories" Type="String" Access="ReadWrite"
Value="Business Competition Expense\ Report Goals/Objectives Ideas In\ Process
Miscellaneous Planning Schedule Travel VIP Waiting" />
<Property Name="_reportinggallerytemplateid" Type="String"
Access="ReadWrite" Value="272be83d-ca0d-46cf-94bf-974311e220aa" />
<Property Name="__CacheProfileListId" Type="String"
Access="ReadWrite" Value="dfdfc9aa-b504-4914-88d6-4761b91129ec" />
<Property Name="__SiteColImagesListId" Type="String"
Access="ReadWrite" Value="963c4dfe-d577-487d-bc1b-56bfe69edc53" />
<Property Name="__NavigationSortAscending" Type="String"
Access="ReadWrite" Value="False" />
<Property Name="vti_usagelastupdatedaycount" Type="Integer"
Access="ReadWrite" Value="39539" />
<Property Name="vti_usagebyday" Type="String" Access="ReadWrite"
Value="1 5 1 0 0 0 2 0 0 0 0 0 1 3 1 0 1 0 0 104 40 96 150 198 139 144 220 73 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 104 116 0 0 0 228 169 84 0 165 156 207
17 143 72 138 77 139 76 153 56 128 85 138 153 173 170 78 251 151 167 120 65 141
79 6 164 45 142 165 166 151 80 161 53 136 155 167 33 140 80 110 166 25 141 148
166 47 159 136 178 189 161 167 168 45 131 88 209 145 160 29 127 45 0 0 0 133 92
158 131 160 133 160 80 160 146 160 129 169 39 124 160 61 130 161 145 138 144 161
84 156 161 160 160 138 181 145 157 89 139 85 206 66 121 131 157 106 158 108 129
175 99 157 152 173 140 166 0 0 29 27 3 1 4 0 0 2 64 18 106 91 0 0 7 20 3 24 0
257 251 257 63 194 49 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 186 285 1134 2303 259 204 1532"
/>
<Property Name="__ImagesListId" Type="String" Access="ReadWrite"
Value="9c3af503-72bd-4a00-953a-6490ca85faf6" />
<Property Name="vti_extenderversion" Type="String"
Access="ReadWrite" Value="12.0.0.4017" />
<Property Name="vti_usagebymonth" Type="String"
Access="ReadWrite" Value="7 1172 1246 3833 3704 3795 3242 1406 0 5903" />
<Property Name="vti_defaultlanguage" Type="String"
Access="ReadWrite" Value="en-us" />
<Property Name="vti_themedefault" Type="String"
Access="ReadWrite" Value="none" />
<Property Name="vti_ignorekeyboard" Type="Integer"
Access="ReadWrite" Value="0" />
<Property Name="_VarRelationshipsListId" Type="String"
Access="ReadWrite" Value="64e7b7ab-9bc3-45f4-a35e-bcfa2926862e" />
<Property Name="vti_usernames" Type="String" Access="ReadWrite"
Value="" />
<Property Name="__NavigationOrderingMethod" Type="Integer"
Access="ReadWrite" Value="2" />
<Property Name="vti_approvallevels" Type="String"
Access="ReadWrite" Value="Approved Denied Pending\ Review" />
<Property Name="__PublishingFeatureActivated" Type="String"
Access="ReadWrite" Value="True" />
<Property Name="__IncludeSubSitesInNavigation" Type="String"
Access="ReadWrite" Value="True" />
<Property Name="SRCH_ENH_FTR_URL" Type="String"
Access="ReadWrite" Value="/SearchCenter/Pages" />
<Property Name="vti_usagehitsbymonth" Type="String"
Access="ReadWrite" Value="7 1172 1264 3833 3704 3795 3266 1528 0 6436" />
<Property Name="__CurrentNavigationExcludes" Type="String"
Access="ReadWrite"
Value="79b40dd8-77f4-42a6-9e33-d6604b3c9df6;234deecf-c0b7-4d39-9491-bd9b5b66c201\
;19418b99-6ab0-4d87-b458-dc2196062331;b8d749d4-860f-463f-8aaf-ce6b96ca58b3;6ddf5\
bab-3ab3-4d93-8281-b302e008eed2;a99bbb57-2746-404b-ab0b-6abb29a6c204;959a39e3-c1\
e8-4ea9-bca8-3b13df216382;58815fd2-17cc-4fb0-82a1-d60146454e56;92ef7150-ff79-484\
b-bcda-fc7e8f80e289;4ac4163f-7389-41f9-9fab-f8ff227ad3de;a7891975-56f2-46af-92dd\
-45cf2144a3ca;" />
<Property Name="vti_siteusagetotalvisits" Type="Integer"
Access="ReadWrite" Value="51473" />
<Property Name="vti_navbuttonnextlabel" Type="String"
Access="ReadWrite" Value="Next" />
<Property Name="vti_usagelastupdatedonet" Type="Time"
Access="ReadWrite" Value="2007-04-04T21:59:59" />
<Property Name="vti_associategroups" Type="String"
Access="ReadWrite" Value="24;25;3;4;5;6;7" />
<Property Name="vti_defaultcharset" Type="String"
Access="ReadWrite" Value="utf-8" />
<Property Name="__NavigationAutomaticSortingMethod"
Type="Integer" Access="ReadWrite" Value="0" />
<Property Name="SRCH_ENH_FTR_SCOPE" Type="Integer"
Access="ReadWrite" Value="1" />
<Property Name="vti_navbuttonprevlabel" Type="String"
Access="ReadWrite" Value="Back" />
<Property Name="_SmtReportsListId" Type="String"
Access="ReadWrite" Value="1fde4dcf-50a8-467b-bae3-bafeae363d38" />
<Property Name="__InheritCurrentNavigation" Type="String"
Access="ReadWrite" Value="False" />
<Property Name="vti_navbuttonuplabel" Type="String"
Access="ReadWrite" Value="Up" />
<Property Name="vti_siteusagetotalhits" Type="Integer"
Access="ReadWrite" Value="56282" />
<Property Name="DefaultSiteDirectoryWebId" Type="String"
Access="ReadWrite" Value="fd79147f-d9cc-43ba-bdaa-063d37decf1a" />
<Property Name="_ReusableContentListId" Type="String"
Access="ReadWrite" Value="3e91e946-84d1-43ec-8358-7f5145fc283b" />
<Property Name="_reportinggallerymetadataid" Type="String"
Access="ReadWrite" Value="103ca77d-1f71-4e6a-a4bc-60647a26ad0a" />
<Property Name="vti_navbuttonhomelabel" Type="String"
Access="ReadWrite" Value="Home" />
<Property Name="vti_usagehitsbyday" Type="String"
Access="ReadWrite" Value="1 5 1 0 0 0 2 0 0 0 0 0 1 3 1 0 1 0 0 104 40 96 150
198 139 144 220 73 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 104 116 0 0 0 246
169 84 0 165 156 207 17 143 72 138 77 139 76 153 56 128 85 138 153 173 170 78
251 151 167 120 65 141 79 6 164 45 142 165 166 151 80 161 53 136 155 167 33 140
80 110 166 25 141 148 166 47 159 136 178 189 161 167 168 45 131 88 209 145 160
29 127 45 0 0 0 133 92 158 131 160 133 160 80 160 146 160 129 169 39 124 160 61
130 161 145 138 144 161 84 156 161 160 160 138 181 145 157 89 139 85 206 66 121
131 157 106 158 108 129 175 99 157 153 174 140 166 0 0 30 48 3 1 4 0 0 2 65 19
173 95 0 0 7 20 3 25 0 257 251 257 63 218 73 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 214 309
1183 2476 259 204 1791" /> etc....