SCOM 2012 Report error rsprocessingaborted rserrorexecutingcommand

Hello All,

I am able to run some reports from SCCM 2012 console but few of them do not work.

Error in SCOM console when I try to run the report

An error has occurred during report processing. (rsProcessingAborted) Query execution failed for dataset 'Data_Warehouse_Main'. (rsErrorExecutingCommand) For more information about this error navigate to the report server on the local server machine, or enable remote errors

When i log on to report server and try to run same report using  browser, here is the error I get

An error occurred during client rendering. An error has occurred during report processing. Query execution failed for dataset 'Data_Warehouse_Main'. The EXECUTE permission was denied on the object 'Win7MemorySufficiencyReport', database 'OperationsManagerDW', schema 'dbo'

So where do we need to change the permissions and for what account?

Also why some reports are running with same permissions and not others?

Thanks in Advance!!