Cannot impersonate user for data source 'TfsOlapReportDS'. (rsErrorImpersonatingUser)
For more information about this error navigate to the report server on the local server machine, or enable remote errors
1. Make sure the account AD\SmartTFSReports for TfsOlapReportDS data source has the correct password configured.
2. Start-> Run-> gpedit.msc-> computer configuration-> Windows Settings-> Security Settings-> Local Policy-> User right assignment-> Access this computer from the network-> check AD\SmartTFSReports account is included.
3. Get more detailed error by logging on to TFS report server, accessing the TFS reports. The detailed error message is: Logon failure: the user has not been granted the requested logon type at this computer.
4. Add AD\SmartTFSReports to administrator group.
5. You could set the "EnableRemoteErrors" configuration value to True in the ReportServer.ConfigurationInfo database table.
Another Problem. Team Explorer - red cross on "documents"-folder
Solution. This is client side problem. Run "devenv /resetuserdata": cleaned the client side cache on my computer under C:\Documents and Settings\