Two Issues:
1) How do you void a cheque after you have posted using manual cheques and retrieved in GL?

2) I used the "prepayment" feature w/ no invoice through manual cheques. It DR AP, CR CASH. Now I have entered an AP invoice and posted. I tried to apply prepayment and invoice through manual cheques to zero out account. I printed cheque and it says, "nothing to print", which is ok. Logically, then you should be able to "post", however, it created error batch because it wanted to print cheque... thus "circular problem"???
2a) Did i go through correct procedure?
2b) How do i correct error?

Thank you.

1) If you want to reverse a check, including the GL entries, then you can do this from the Check Reconciliation function. Make sure you choose to 'Reverse' the check status, rather than 'Void' it, because Reversing will automatically generate the reversing GL transactions.

2) I'm assuming that when you posted the Pre-payment, you did not include an Invoice number as an applied document. You don't have to do this.
After posting the Pre-payment and the invoice, it sounds like you followed the correct procedure; creating a zero dollar cash entry and apply it to both the invoice and the pre-payment.

Make sure that you do not have the 'Print Check' checkbox selected on this last check because you don't really want to print it. Also make sure that you enter something into the Check number field because it cannot be blank. You should then be able to post that entry - to be sure, make sure that it is the only check in the batch.

Regards,