Error while transfering data to Apps server

HI !

I have created an exit to transfer the data of a query directly onto the apps server and I get this error. Could anyone pls let me know how to rectify this please.

An exception occurred that is explained in detail below.

The exception, which is assigned to class 'CX_SY_FILE_OPEN_MODE', was not

caught in

procedure "EXIT_RSAQEXCE_001" "(FUNCTION)", nor was it propagated by a RAISING

clause.

Since the caller of the procedure could not have anticipated that the

exception would occur, the current program is terminated.

The reason for the exception is:

When accessing the file "/NAL.LOCAL/APPLICATION/SAP/IFACESDEV/QUERYOUT", the

system recognized that this file is

not open. Therefore, the file cannot be accessed.

* Retrieve the app server filename
select single low into l_file
    from tvarvc
    where name = 'Z_QUERY_DOWNLOAD_FILENAME'.

open dataset l_file for output
  in text mode encoding default.

* Transfer the data
loop at datatab.
  clear <ls_row>.
  move-corresponding datatab to <ls_row>.
  transfer <ls_row> to l_file.
  append <ls_row> to <lt_table>.
endloop.

close dataset l_file.

Thanks