BPEL error while creating Drop Ship Order

We are testing Drop Ship Sales Order, however we are facing this error while creating the Sales Order at the Procure Task, Create Purchase Requisition Step:

com.oracle.bpel.client.BPELFault: faultName: {{http://schemas.xmlsoap.org/ws/2003/03/business-process/}selectionFailure} messageType: {{http://schemas.oracle.com/bpel/extension}RuntimeFaultMessage} parts: {{ summary=<summary>The <from> value is invalid. The result of from-spec is null. Either the from node value or the xpath query in the from node value was invalid. According to BPEL4WS spec 1.1 section 14.3, the from node value should not be empty. Verify the from node value at line number 2,010 in the BPEL source. </summary> ,activity=<activity>97182265-BpAss92-BpSeq60.85-1</activity> ,query=<query>bpws:getVariableData('OnMessage_processResponse_InputVariable','payload','/ns30:processResponse/ns10:headerTL/ns10:FulfillLineTLVO1[$stepIndex]/ns10:FulfillInstanceId')</query> ,lineNumber=<lineNumber>2010</lineNumber>}