Been searching for 3 hours and getting no where - some what of a newbe..

What am I trying to do ?

On Sharepoint 2007

Wish to access Excel files stored on a file server using UNC paths - simple
or so I thought...

have set up trusted file location

eg file:\\fileserver1\files

type UNC
trust children =Yes

Then I go to a PC - access the web site - edit Excel web component
go to browse a workbook location

type file:\\fileserver1\files in the URL
press the arrow icon
"Cannot find this location in the current site collection"

When I try the "..click the URL to open in a new browser:
file:\\fileserver1\files"
I get no issue - can see the files without issue or prompt for password

I am missing something very obvious -
anyone know ? or point me at a "How to article"