Data error? i think

I entered a credit memo for a customer. If I run the customer transaction report I see the value in the report. If I run the trial balance report in the general ledger and analyze the receivables account the transaction (CM1) shows a nil value, but if I view the line to see the underlying credit memo it shows a value ! So my customer screen doesnt balance with the g/l receivables account. Is there any way I can fix this. If there was a way to reverse the transaction that would be fine provided the reversal also made the same error.

Thanks

Tony Bird