Reject Workflow Item Via BAPI

We are trying to implement functionality to reject a workflow item. We are using a BAPI to release and item.

Can you set the workitem status to rejected with SAP_WAPI_SET_WORKITEM_STATUS?

We attempted to use SAP_WAPI_REJECT_WORKITEM but the funtion states that our workitems cannot be rejected because it is the wrong type.

Any suggestions would be appreciated.