Hi,
I think you may try EHAUADR_STREET4 because there is no STREET5 field in structure BAPI_EHAUADR and address fields description may be misleading (description "street 2" corresponds to field "street1"). Also be aware that a very good cookbook explaining how to setup the IS-U/CRM integration for technical objects is available at http://service.sap.com/utilities.
Regards,
Nicolas.