regarding form script

Hi to all,

I am creating a smart form with three window:

address

main

footer.

i am using loop for address and main window as loop1 and loop2.

in loop1 and loop2 i am writting JTAB INTO JTAB.

I AM USING KNA1 TABLE.

AT SELECTION SCREEN I AM USING SELECT-OPTIONS FOR KNA1-KUNNR.

WHEN RUNNING THE PROGRAM I AM GETTING ALL THE ALL THE CUSTOMER DETAILS IN ONE PAGE. NOT ON DIFFERENT PAGE FOR EACH CUSTOMER.

WHY IT HAPPENS .

ALSO TELL ME THE ROLE OF LOOP IN PROGRAM.

THANKS