error : the IN operator with "S_EBELN" is followed neither by an itab nor by a value list

Hi gurus ( this is my first question in here )

i m trying to develop an alv program and getting an error as mentioned in the subject.

please help me.

*** program's select options is :

SELECTION-SCREEN BEGIN OF BLOCK A1 WITH FRAME TITLE TEXT-B01.

select-options : s_ebeln for ekko-ebeln.

selection-screen skip.

parameters : p_LIFNR type EKKO-LIFNR obligatory.

SELECTION-SCREEN END OF BLOCK A1.

*** my itab definition is :

data: lt_ekko type table of ekko,

lwa_ekko type ekko.

and the error is in the foto