Printer tray names

We want to show the possible printer tray names and try to use DeviceCapabilities from winspool.drv.

If I enter the  debugger and step over the DeviceCapabilities-call it works perfectly - again and again as long as I stay in the program.

If the call is executed without entering the debugger I get a "memory access violation".

Here is the code:

       01            WK-WINSPOOLDRVJN  PIC X(01).

       01            WK-TRAYTABELLE.
           02        WK-TRAYSATZ       OCCURS MAX-PAPER-TRAYS.
            03       WK-TRAYNAME       PIC X(24).

       01            WINSPOOL-PRINTER  PIC X(80).
       01            WINSPOOL-PORT     PIC X(80).
       01            WINSPOOL-FC       PIC 9(4) COMP-5.

=================================================================       
           MOVE "J"                    TO WK-WINSPOOLDRVJN.

           CALL "c:\Windows\System32\winspool.drv"
           ON EXCEPTION
                MOVE "N"               TO WK-WINSPOOLDRVJN
                GO TO PCPDRU10MEDIA-WINPRINT
           END-CALL.

           MOVE WRAL50-COMBOZEILE      TO WINSPOOL-PRINTER.
           INSPECT WINSPOOL-PRINTER    REPLACING TRAILING SPACES
                                       BY X"00".

           MOVE WINPRINT-PORT          TO WINSPOOL-PORT.
           INSPECT WINSPOOL-PORT       REPLACING TRAILING SPACES
                                       BY X"00".
                                       
           MOVE SPACE                  TO WK-TRAYTABELLE.
           MOVE 12                     TO WINSPOOL-FC.

           CALL "DeviceCapabilitiesA"  USING
                BY REFERENCE  WINSPOOL-PRINTER
                BY REFERENCE  WINSPOOL-PORT
                BY VALUE      WINSPOOL-FC
                BY REFERENCE  WK-TRAYTABELLE
           ON EXCEPTION
                MOVE "N"               TO WK-WINSPOOLDRVJN
                GO TO PCPDRU10MEDIA-WINPRINT
           END-CALL.

           IF   WK-TRAYTABELLE         = SPACE
                MOVE "N"               TO WK-WINSPOOLDRVJN.

Do you see my error or do you have a tip for me ?

              
Thanks in advance for your support.

Andreas