Problem with output type--urgent

Hi experts,

My requirement is i need to post a vendor lkiability. For that we create a output type 'ZALV'. We also created a report program . In nace we attached the program and output type with medium '8'. we call the same subroutine Entry which available in standard program (CMSR_OUTPUT_ENTRY whcich is attched to medium 8 and o/p type:CMSF). Up to this one my output type works fine and processed successfully.In that Entry some function modules called.

When i added my own code in report program it gives a error

saying that ' POSTING_ILLEGAL_STATEMENT".

Statement "CALL SCREEN" is not allowed in this form.

There is probably an error in the program

"SAPLTAX1".

This program is triggered in the update task. There,

following ABAP/4 statements are not allowed:

- CALL SCREEN

- CALL DIALOG

- CALL TRANSACTION

- SUBMIT

In my code i am not used these statements also.

The error in code is:PERFORM skftabn_ergaenzen.

xbset-first = 1.

xkzinc = space.

IF bkpf-xmwst = 'X'.

ok-code = 'CALC'.

IF bkpf-xsnet = space.

xkzinc = 'X'.

ENDIF.

ELSE.

ok-code = 'PRUF'.

ENDIF.

IF i_xsimu NE 'S'.

xnodia = 'X'.

ELSE.

xnodia = space.

ok-code = 'SHOW'.

ENDIF.

-

Bild dunkel prozessieren -

evtl. veraenderte Steuern merken

IF xusvr = 'X'.

PERFORM ustaxes_detail USING i_bkpf.

ELSE.

IF sy-tcode(1) = 'M'

or bkpf-tcode(1) = 'M'.

OR bkpf-tcode(1) = 'M' OR NOT dynpro_501 IS INITIAL.

CALL SCREEN 301.

ELSE.

CALL SCREEN 300.

ENDIF.

ENDIF.

ok-code = space.

Please give me a solution --- It is very urgent.

Regards

Pratap.M