Clarification Posting with Payment Specification as the Selection Parameter

if the Payment Specification Amount is = to Clarification Payment Lot Amount the posting is happening, If I am not wrong the Partial Clearing will not work with Payment Specification but How about the Over Payment ?

Payment Lot Amount is - 600 USD

Payment Specification Amount is - 550 USD.

I want to clear the Payment Specification amount of 550 from the 600 Payment and post Extra 50 USD into "ON ACCOUNT'

not able to post on Account after check marking the --> Special usage / On Account (Error - No assignment of amount 600,00- USD possible due to selection specifications)

tried with Posting online --> On Account --> its giving the Error of GL Account can not be determined (PA S001 is maintained for CC+AD+MT+ST)

Could you please advise on this subject, Thanks.