Module Pool Selection Screen

Hi Experts,

i have created a screen(100) and in that i created sub screen area

and i created a subscreen(101)

i write the code i mentioned below

TABLES : EKKO , EKPO .

SELECTION-SCREEN BEGIN OF SCREEN 0101 AS SUBSCREEN.

PARAMETERS :     P_BUKRS TYPE EKKO-BUKRS OBLIGATORY DEFAULT '1000'.

SELECT-OPTIONS : S_EBELN FOR EKKO-EBELN ,

                 S_EBELP FOR EKPO-EBELP .

SELECTION-SCREEN END OF SCREEN 101 .

&----

*&      Module  USER_COMMAND_0100  INPUT

&----

•       text

----

MODULE USER_COMMAND_0100 INPUT.

  CASE SY-UCOMM.

    WHEN 'BACK'.

      LEAVE PROGRAM.

  ENDCASE.

ENDMODULE.                 " USER_COMMAND_0100  INPUT

for flow logic i write like this

PROCESS BEFORE OUTPUT.

• MODULE STATUS_0100.

  CALL SUBSCREEN SUB_SCREEN INCLUDING SY-REPID '0101'.

*

PROCESS AFTER INPUT.

  CALL SUBSCREEN SUB_SCREEN.

  MODULE USER_COMMAND_0100.

it shows an error like

Error when generating the selection screen "0101" of report '<report Name>'