Trigger Workflow using Function Modules

I have created my first custom workflow, and all I need to do now is trigger the WF from a user exit. But I can't get the FM's to trigger my event.

- I have created an event (ZUPDATE) in SWO1 for my ZYD_ERRORS object.

- I have added this event to SWETYPV

- And i am using SWE_EVENT_CREATE_IN_UPD_TASK to try and trigger my WF.

- but when checking SWEL no event is triggered.

I am unsure of the parameters I should be using in SWE_EVENT_CREATE_IN_UPD_TASK . I am passing in ZUPDATE (event) and ZYD_ERRORS (object), but don't know what the objkey parameter should be.

Please help.