are you using ro-adapter-http for SOAP web service call? You should be using ro-adapter-ws SOAP web service calls.
Also, In you adapter request I can see an element <error-message /> which shouldn't be there, please remove it and try again with correct adapter.
Why don't you use SOAP Request Method One workflow?
Try using JAXWS message mode approach instead of payload mode (replace soap-body-content to soap-message).