Hi Rama,
For you one create the Sub screen in your program after creating and define your selection screen parameter inside the subscreen and After defining all the parameter in the subscreen.
Call the subscreen in the Main Program. Automatic your Input parameter are working as normal.
Define the selection screen as a SUBSCREEN.
Selection-Screen Begin of Subscreen..............9010..
Selection-screen End of subscreen.
In the initialization method,
Call the screen '9001'. " it the main screen
now in SE51 open the 9001 screen,
In the PBO of the Screen .
Call the SUBSCREEN '9010' using Program
and in PAI.
Call SUBSCREEN 9010.
After that your program is working fine,
Let me know if you have furthur issue.
Regards.
Nishant Bansal.