Error when creating PO with reference to PR

Hello Expert,

When creating PO with reference to PR I encountered with one error i.e. system is taking into consideration one to one relation of PR line item to PO line item. For example: I have created PR with one line item for XYZ value and with reference to PR line item I am creating one PO but with two line items in PO that means I am splitting PR value into two line items in PO, 1st line item with zero tax and second one is with tax.

So there is one PR line item but in PO I am creating two line items with reference to single PR item. In this case system is giving error saying Item 001 WBS element XXXXXXXXXX budget exceeded. message no: BP604. However if I create single line item in PO then it wont give any error.

Please suggest any customization setting is done for such kind of behavior of the system.

Thanks

Shyam