Declaration for smart form importing structure

Hi to all experts,

I have to create a structure for smart form to declare it in the smart form interface (importing ) .The structure should be of the type below. I tried but getting type mismatch dump ....please help

DATA: BEGIN OF ZISEG OCCURS 20.
        INCLUDE STRUCTURE ISEG.
DATA: BTEXT LIKE T064B-BTEXT.           
DATA: GIDAT LIKE IKPF-GIDAT.           
DATA: MAKTX LIKE MAKT-MAKTX.         
DATA: STEXT LIKE T064T-STEXT.         
DATA: NAME1 LIKE T001W-NAME1. 
DATA: END OF ZISEG.