Payables Approval is not validating the invoice

Hi All,

When we run the Payables approval program generically by just giving the OU value alone, the program is throwing the below error for some of the invoices.

"The system cannot prorate this tax amount because the header level control tax amount is not equal to 0, but the total calculated tax amount for this transaction is 0. Please contact your tax manager."

But  when we run the Payables approval for the invoices specifically ,it is getting validated .   The issue is only with one OU .Can someone advise on where i have to look to sort out the issue.

Thanks

Edwin.