Cannot add Customer to a Journal Entry

Hey NS,

We have a deferred revenue entry that was credited by accident as 'Revenue' using the Rev Rec module.

$100 Debit Deferred Revenue
  $100 Credit Deferred Revenue (meant to Revenue against a specific customer).

Then the period closed..... fast forward 6 months later:

We attempt to fix the mistake:

$100 Debit Deferred Revenue (We NEED to put against a customer here!)
    $100 Credit Revenue

If we can't put a customer here, we see in our Deferred Revenue By Customer Detail Report as 'Non-Entity' and therefore doesn't offset.

Ideas?
LN