Merge Statement (COBOL)

I was working on a program that needed to use a merge statement to put two files together and sort them. Of course though I would not be here if I didn't have a problem. When I run my program I have to do a little work afterward to add to the output. When it it goes to perform that paragraph it gives an error that says "Merge File out of sequences ORDER-FILE-SOR". Here is my code:

   100-MAIN.
       MERGE ORDERS-FILE-SORT
             ON ASCENDING KEY REQUEST-DATE-S
             ON ASCENDING KEY CUST-NUMBER-S
             ON ASCENDING KEY CUST-ORDER-NUMBER-S
             ON ASCENDING KEY PART-NUMBER-S
             USING ORDERS-FILE-PRIOR-IN
                   ORDERS-FILE-NEW-IN
             OUTPUT PROCEDURE 200-FILE-START
       STOP RUN.


   200-FILE-START.
       OPEN OUTPUT ORDERS-FILE-OUT

       ACCEPT WS-DATE FROM DATE
       MOVE RUN-MONTH TO MONTH-1
       MOVE R开发者_如何学JAVAUN-DAY TO DAY-1
       MOVE RUN-YEAR TO YEAR-1

       PERFORM 300-NEXT-PAGE

       PERFORM UNTIL ARE-THERE-MORE-RECORDS = 'NO '
           RETURN ORDERS-FILE-SORT
               AT END
                   MOVE 'NO ' TO ARE-THERE-MORE-RECORDS
               NOT AT END
                   PERFORM 400-PROCESS-FILE
           END-RETURN
       END-PERFORM.

       CLOSE ORDERS-FILE-OUT.

The output it does show is the heading line and it seems to stop at the "RETURN ORDERS-FILE-SORT" line.

Any help would be greatly appreciated as I feel the rest of the program will run just fine, but I can't check it till this is fixed.

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The MERGE verb combines two or more identically sequenced files. To have it work, you must have already sorted them according to an identical set of ascending/descending keys.

If your input is not already in that order, you might need to sort each file by REQUEST-DATE-S, CUST-NUMBER-S, CUST-ORDER-NUMBER-S and PART-NUMBER-S