Do you even get to the opening list?  Can you try in a different company?  It is opening the same files as Service & Repair but then the actual orders listed will exclude Service & Repair .

You probably don't want ti initialize it, it is the same table as Service and Repair and I know you use that.  But if there are entries with a 0 Number, manually deleting them might help.  At least if it opens in other companies, we know it is something with the data.

Yes, RMA is using the same tales as S/R.  Converting an RMA to a S/R order will simply change a status flag on the order.  The old add-on RMA used the Sales Quote file.

We figured it out and will send you a patch.  It is related to having more than 13 S/R orders in the file and no RMA orders (yet).  It gets to the end of file with no valid RMA entry so it quit rather than show an empty list.

Pretty cool. Works slick until I get to RM-D. No matter what I put in (Y or N), the program terminates and the status in ISSR.INV.INVCD stays "R". I don't see a field in the ISSRINVL file to record the status of each line.
 
UPDATE: The above test was done in our test company. Subsequent testing in live company worked fine. I like it! More testing to follow.
 
I did note with interest that it uses the S/R register for numbers. Excellent.