Two Way Matching for Amount Only PO's

Hello,

I am testing as part of upgrade from 9.1 to 9.2 this functionality. My client has this need for 2 way matching where a blanket PO (amount only) for services is invoiced multiple times. As part of testing I created Amount Only line item with 1000 as PO. I invoiced for 500 and ran matching but is running into pricing exception since the amount (1000 on PO not matching 500 what is invoiced). We are using delivered functionality and Standard Match Rule. I am under the assumption that this Voucher should have matched. Any idea what is it I am doing wrong? Any information is appreciated.