invoice approval status remains future, after initiated

select * from wf_item_activity_statuses

where item_type = 'APINV'

return empty rows

1. staff initiate approval of invoice

2. can see next approver (supervisor) in invoice approval history

3. but supervisor never get notification to approve / reject that invoice

i have run workflow agent listener. only running. never ends.

i read at metalink. i need to run WF data loader. but i do not know what should i fill in parameter mode and file

please help. thanks