problem in executing a smartform URGENT!!

HI,

I created a template in my layout and created a structure

z_tab which i had to pass in the smartform now

my problem is

in form interface i gave i_tab type z_tab

and in template-> text iam adding a feild&i_tab-raw&( this is my feild name which i have to show in output) and in se38 my interface program i gave the necessary.

But iam getting error saying

"Reference field I_TAB-RAW unknown in form."

please help its urgent

Thank you