When submit button clicks the mail shoud trigger in workflow.

hi,

I created a module pool program , in there i have some fields. by giving f4 help in key fields all other values ll come. after that if i click submit button the workflow want to trigger. i created on bo . in that i specify the key field, and i create event called submit. for that event i gave key field as a  parameter. I c

in submit i ll call this fm SAP_WAPI_START_WORKFLOW . in task i give the workflow which i created.but its not triggering.

Regards,

gopi