Data Driven Subscription - rsLogonFailed Problem

Hi
I am working my way through a series of tutorials in RS2005 and am
having a problem when trying to create a data driven subscription
When I try to validate my query against a subscriber database I get :
Logon failed. (rsLogonFailed) Get Online Help - Value does not fall
within the expected range.
The connection I am using is:
data source=(local);initial catalog=AdventureWorks; persist security
info=false;Application Name=SalesPeopleSub;password=sp_password
I have then entered some user credentials and checked 'Use as Windows
credentials when connecting to the data source'.
This connection method is exactly the same as I used when I created a
custom data source for another report earlier in the tutorial and this
works fine.
The query I am using is:
SELECT
FILENAME, FILEEXTN, PATH, RENDER_FORMAT, USERNAME, PASSWORD, WRITEMODE
FROM DataDrivenFileShareExample
As far as I can tell I have given my user enough rights to read from
this table. I have even used the runas.exe app to launch the SQL
Management Studio using the users credentials and can successfully run
that query from the Query analyser.
if anyone can point me in the rightv direction it would be appreciated
Cheers
MarkI have since found that if I create exactly the same data source as a
shared data source, I can select it and successfully use it in the data
driven subscription.
So it appears to be a problem with setting a individual data source for
a data driven subscription only. Can anyone could shed any light on why
if fails?
Cheers