Errors on reports rendered by SQL Server Reporting Services 2005 and 2008 will not give you the full details of the issue if you are browsing on a machine other than that hosting SSRS. Instead, you just get this:
With SSRS 2005 you had to manually edit a web.config or run code (SQL or other) in order to get more details beyond the SSRS box. Jim (Saunders) showed me something cool today in SSRS 2008 however:
Setting EnableRemoteErrors here to TRUE will get you full report error details on remote clients. You access this screen via SQL Management Studio. Connect to SSRS, right-click on the server instance in Object Explorer and select “Properties”.
Hope this helps