I just wanted to add some details in the above issue to make it more clear.

I have 2 different membership provider i.e 1)AD users  2)ADAM users and i
wanted to separate users between these 2 sites.

I am using the below STSADM command but it doesn't work.

stsadm -o setproperty -url http://<server> -pn
"peoplepicker-nowindowsaccountsfornonwindowsauthenticationmode" -pv yes

I am using the below site  as a reference.
technet.microsoft.com/en-us/library/cc263264.aspx

Here I am also giving you my membership provider web.config:

<membership defaultProvider="adammembership">
<providers>
<add name="adammembership"
type="Microsoft.Office.Server.Security.LDAPMembershipProvider,
Microsoft.Office.Server, Version=12.0.0.0, Culture=neutral,
PublicKeyToken=71E9BCE111E9429C" server="server1" port="389" useSSL="false"
userDNAttribute="distinguishedName" userNameAttribute="cn"
userContainer="OU=ADAMTest,O=ADAM,C=US" userObjectClass="user"
userFilter="(ObjectClass=user)" scope="Subtree"
otherRequiredUserAttributes="sn,givenname" />
</providers>
</membership>