Adobe form as attachment to user decision step

Hi,

i need to add adobe form as attachement to user decision step in workflow.

1. i created activity step which call business object method with parameters workitem id

     i am using FM  SAP_WAPI_ATTACHMENT_ADD’  which will return attribute id

     i am passing that attribute with document id to 'ZSOFM'

        ZSOFM <-----------------------------------ZSOFM (Method to task)

      Bindings 'Attach_objects'  <------------- ZSOFM(Task to Workflow).

2. i created user decision step

    Bindings  'Attach_objects' --------------------> 'Attach_Objects'( Workflow to user decision task).

but when we execute first activity step in background i am not getting any PDF output .but when we  execute same method from class i can see pdf data is coming is it due to user name WF-Batch.

when i execute activity step in back ground which will have sy-uname as WF-Batch i am not getting any PDF output data.

please help how to solve .

Thanks,

Phani