Error in Control Framework in smart forms programms

Question

IN VF02 smartforms ENTRY form , I add a function about save PDF at local PC. When I print the smartfomrs,There is ERROR message in update modules.
IN SM13 can see the ERROR message. 
Function Module: RV_MESSAGE_UPDATE
Status :Update was terminated
Error details: FES 022: Error in Control Framework
THE CODE:
FORM processing USING proc_screen
                CHANGING cf_retcode.
******I ADD THE CODE
       PERFORM DOWNLOAD_AS_PDF USING lf_fm_name
                                     ls_control_param
                                     ls_composer_param
                                     ls_bil_invoice
                                     nast
                                     repeat
                                     ls_bil_invoice-HD_ORG
                                     ls_spoolid
                                CHANGING cf_retcode
ENDFORM.
IN DOWNLOAD_AS_PDF  FORM ,I USE FUNCTION : P_fm_name(smartforms function)   CONVERT_OTF   GUI_DOWNLOAD
WHY the UPDATE MODULE have ERROR MESSAGE???
How do I solve this problem？？？

Answer 1

Hello,
Your error message is related to GUI_DOWNLOAD, which is a frontend function.
You simply cannot use it in background, because it puts a file on the
frontend PC where you start the function (WS = WorkStation).
Note that GUI_DOWNLOAD is intendted to be used for dialog user
and will not run at BACKGROUND.
You can review SAP Library: ABAP Programming (BC-ABA)
->Saving Data Externally
  ->Working with Files
    ->File Handling in ABAP
Regards,
David