assigning smartform for sales promotion notification

having a requirement where i need to change the standard sapscript given by SAP for Sales Promotion with the new custom smartform output.

Trying to assign a smartform for standard output type RTB2 using WB/D & WB/B. However, It is not working. I am providing the customer driver program and form routine name where i m calling smartform and a smartform name with the type as smartform. But it is not working.

Is this possible to call smartform because when i debugged SAP is calling routine "ENTRY_GROUP_NAST_SIMUL" though in standard settings form name assigned is ENTRY_GROUP_NAST or ENTRY_SINGLE_NAST for different output types.

Please help me in calling the smartform for the output for sales promotion notification.

Thanks,

Janisar