How to create an activity using business partner of document flow

hi guys,

Can anybody help me how to create an activity by using the business partner of document flow.

i am using the function module BAPI_ACTIVITYCRM_CREATEMULTI but it was giving some sort of error in level based.

so if anybody used above type of scenario can help me out. if you have an sample code please post it which is very much usefull..

thnaks

viswam