The source and target structure have a different number of fields

Question

Hi,
I am new to workflow and I am trying to create an attachment in Workflow (SAP ECC 6.0) and pass it through to a User Decision (User Decision works fine) however the workflow is failing on the attachment step with u2018The source and target structure have a different number of fieldsu2019. The bindings check ok. Please see details below.
I have used document u2018Creating Attachments to Work Items or to User Decisions in Workflowsu2019 by Ramakanth Reddy for guidance. Thanks in advance.
1) Workflow containers (SWDD)
WORKITEMID (import)
ZSWR_ATT_ID (export)
SOFM (export)
2) Task Container (PFTC)
1 Import parameter defined u2013 WORKITEMID (swr_struct-workitemid)
2 Export parameters defined
- SOFM (Ref. obj. type SOFM)
- ZSWR_ATT_ID  (swr_att_id-doc_id)
Binding task -> Method
Binding for 1 parameter (import) defined
Task <- Method
Binding for 2 parameters (export) defined
3) Z  BOR object created with a Method, Method Parameters and Event (SWO1)
1 import parameter defined
2 export parameters defined
Method calls FM SSF_FUNCTION_MODULE_NAME, CONVERT_OTF, SCMS_XSTRING_TO_BINARY and SAP_WAPI_ATTACHMENT_ADD
Workflow is triggered by FM SAP_WAPI_CREATE_EVENT, Return_code = 0
Event_id = 00000000000000000001
Test results
A) Triggered by ABAP/ FM SAP_WAPI_CREATE_EVENT - SWI2_DIAG results
Work item  14791: object <z bor object name> method <method name> cannot be executed. The source and target structure have a different number of fields (this message is repeated 3 times). Error handling for work item 14791. No errors occurred -> details in long text (message is repeated 3 times).
Message no. WL821, OL383, WL050 in long text
B) Z BOR Test method <execute>
Enter workitem id.
Runtime error - Data objects in Unicode programs cannot be converted. The statement "MOVE src TO dst" requires that the operands "dst" and "src" are convertible. Since this statement is in a Unicode program, the special conversion rules for Unicode programs apply.                                        
In this case, these rules were violated.   
Program                             SAPLSWCD                
Include                                LSWCDF00                
Row                                    475                     
Module type                        (FORM)                  
Module Name                      MOVE_CONTAINER_TO_VALUE           
C) Z BOR Test method <debugging>
Enter workitem id.
SAP_WAPI_ATTACHMENT_ADD, return_code = 0, message_lines  = Attachment created            
both  swc_set_element container work ok
Runtime error occurs after end_method executed. Data objects in Unicode programs cannot be converted.
D) Workflow test
Enter workitem id <execute>
Task started> Workflow log> Status = Error
Workflow errors in Attachment step (however Office document can be viewed in details for step).

Answer 1

Problem has now been resolved. Problem was related to use of swr_att_id structure and swc_set_element statement in BOR program - problem resolved by only setting w/f container to swr_att_id-doc_id.