GR/IR account G/L balance does not match with BSIS table

Hi,

I am preparing a report which uses table BSIS.But the total in the table does not match with the GR/IR G/L balance account.When I click on balance item display in FS10N the entries match with that of BSIS but the total is different.Also how to factor the year opening balance entries in the report.

Thanks

Arun