at selection-screen on radiobutton group is triggering again on execute??

Hi Friends,

I want to show a Information pop up on selection of a radio button for that i have done

AT SELECTION-SCREEN ON RADIOBUTTON GROUP RG.
  IF P_UPL = 'X'.

    CALL FUNCTION 'POPUP_TO_INFORM'
      EXPORTING
        TITEL = TEXT-017
        TXT1  = TEXT-015
        TXT2  = TEXT-016.

  ENDIF.

I have two radio buttons and second radio button is P_UPL. Its working fine.

But same event is getting triggered when execute button is pressed( i mean when report is executed ), which i don't want.

How to restrict.

Any help is greately appreciated.

Thanks,

Simha