How do I create reports that show updated Purchase Order balances?

For Example, if I have a Purchase Order for $100 and a paid Invoice for $40, how would I be able to see this $60 balance? This invoice has been applied to the purchase order.

Currently, I am able to see the "Pending Purchase Order by Vendor" reports, which show the $100.  I am also to see the invoice on a separate report for $40 but not both of them together and the $60 outstanding on this Purchase Order.  Am I posting something wrong perhaps?

Any suggestions would be greatly appreciated!

Thanks

The report is not available in Simply.

You would have to design or have someone design a Crystal Report to obtain this info.