Variable in selection screen

Question

Hi
   I have two fields one for reporting period and another for Creation date on which user can seletct on selection screen(variable).  I have made both of the variable mandatory so that if user does not enter value any one of them , it is showing message to make an entry in all required fields.
Now user wants               
                      1. If user enters value in any one of the seletcion field and keep other field blank, report 
                          should display without giving error message. But if he keeps both fields blank and 
                         execute report, it should display error message to enter value in required field.
Can anybody please guide me is it  possible?
If i make one field(reporting period )mandatory and other(Creation date ) optional,  when user will execute report without giving any value in reporting period , it will show message to make entry for Reporting Period.
Regards
Deep

Answer 1

Hello Guys,
i am facing an issue with pop up of error message on the screen after validation. here is my code
case i_step.
    when 3.
      loop at i_t_var_range into lv_temp.
        if lv_temp-vnam = 'ZCUR_TYP'.
          var1 = lv_temp-low.
          exit.
        endif.
      endloop.
      clear: lv_temp.
      loop at i_t_var_range into lv_temp.
        if lv_temp-vnam = 'ZVEXRATE'.
          var2 = lv_temp-low.
          exit.
        endif.
      endloop.
      clear: lv_temp.
     loop at i_t_var_range into lv_temp.
        if lv_temp-vnam = 'ZVICOMPC'.
          var3 = lv_temp-low.
          exit.
        endif.
      endloop.
     select single * from /BI0/PCOMP_CODE into compcode where
             COMP_CODE = var3.
      if sy-subrc = 0.
        if compcode-currency  = var1
            and var2 ne ''.
            MESSAGE E000(ZBW).
        endif.
      endif.
endcase.
when i try to texecute this code, i am getting disconnected from BW with a message connection closed without message (CM_NO_DATA_RECEIVED)
its working fine in RSRT. i get the message at the bottom in the scrol bar.
please let me know if there is any thing wrong inthe code.
Thanks
Krishna