Help with AR Offline Load

We are trying to use the AR Offline load feature to bring credit memos into
Mapics.    Most of the credits we issue are against 
invoices that have already been PAID.    It appears from our testing that
you're not able to utilize the "Invoice Reference" 
field for invoices that have already been paid.    This doesn't seem
right... I'm sure we're either doing something wrong or 
need to set an option in Mapics someplace.    When you enter C/M's through
COM, you are able to utilize the invoice 
reference field even when the invoice has been paid.   It doesn't make any
sense that you wouldn't be able to do the same 
thing using the AR Credit Memo Entry process.   When we load the offline C/M
batch we get a message "W AM-3515 
Amount/Reference No.   Do not match."   Then we go into the batch using
Invoice/Credit Memos Entry and bring up the 
transaction.    When we press the ENTER key we get the message "E AM-3513
Invoice Reference Not an invoice."    
However, when we look at the customer inquiry we can see the PAID invoice
right there as big as life!   If we repeat the 
same process for an OPEN invoice it seems to work fine.   Does anyone have
any insight on this?   We really need to have the
C/M tie to the original invoice number even if the invoice is already paid.
 
TIA
 
Bud Roble
CR Technical Services
broble@xxxxxxxxx <mailto:broble@xxxxxxxxx> 
(805)794-3027