Executing a Standard Task from program using SAP_WAPI_START_WORKFLOW

Hi experts ,

Can we Execute a Task using Function Module SAP_WAPI_START_WORKFLOW ? Actually I'm trying to execute a standard task TS93100170 using this function module but getting return code 4 with message 'E You are not one of the possible agents of task 'TS93100170'.'

This task is  Background task .

Thank you in advance.

Biswajit