SSRs with SharePoint Integrated mode

Hi all,
have any one encounter this error in SharePoint Integrated mode:
on the share point site. when i try to create Data Source it gives me error bellow in reporting service log files:

w3wp!library!5!08/15/2007-07:44:22:: Call to CreateDataSourceAction(tesr333.rsds, http://sharepointserver/sites/testsite/Data Sources, False).
w3wp!library!5!08/15/2007-07:44:22:: i INFO: Catalog SQL Server Edition = Enterprise
w3wp!security!5!08/15/2007-07:44:29:: i INFO: Exception while running with elevated privileges
w3wp!security!5!08/15/2007-07:44:29:: i INFO: Access is denied. (Exception from HRESULT: 0x80070005 (E_ACCESSDENIED))
w3wp!library!5!08/15/2007-07:44:29:: e ERROR: Throwing Microsoft.ReportingServices.Diagnostics.Utilities.SharePointException: Report Server has encountered a SharePoint error., ;
Info: Microsoft.ReportingServices.Diagnostics.Utilities.SharePointException: Report Server has encountered a SharePoint error.

how can i solve it!!
thanks

Hi Satya,
We followed that and i used that too.
My Report server currently runs under NR Server account and when i try to go on SharePoint site and try to add data source it error out. and in reporting service log i see the error i poster.
If i run my Report Server under Domian/acct it runs fine but when i try to go to http://servername/reportserver. I get error that user not found. along with Report Server has encountered a SharePoint error. ---> Report Server has encountered a SharePoint error. User not found.while the user that running report server is part of Domain Admin group!!!
thanks