Problem with Report Builder reporting from a remote database

Hi All,
I had the same problem with an earlier build of SQL Server.
The data for my report model is located on a different server than SQL Server 2005. On the SQL Server 2005 server I can use the Report Builder and it works just fine.
When I try to run the Report Builder on my desktop I get the following error:

For more information about this error navigate to the report server on the local server machine, or enable remote errors
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Cannot create a connection to data source 'dataSource1'.
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An error has occurred during report processing.

What needs to be in order for users to build reports whose data is located on a different server than SQL Server 2005?

Thanks for your help,
RoyMy guess is you are using Windows Integrated Authentication for connection to both the model and its data source. This won't work if you have two "hops". The typical practice is to store credentials for a user with read-only access to the database on the datasource, and use integrated authentication on the model.