Only can create report using Administrator in Report Server

Hi all,
I am newbie in SSRS and using MS SQL 2k8 Report Manager to create some reports.

I already create some report using BIDS, display, and launch them in Report Manager using UserID Administrator from window where i installed the Report Engine.

But i face trouble when i using a new UserID i created in window and MS SQL.
i can login to Report Manager but have an error message:

An error has occurred during report processing. (rsProcessingAborted)
    Cannot create a connection to data source 'AdventureWorksLT'. (rsErrorOpeningConnection)
        Login failed for user 'xx\xxx'.

Can someone help me to solve this issue?

thank
Yunan

Did you give the new login access to the ReportServer database?