Hello Tony,
The wiki page and the troubleshooting guides give a lot of help on this topic. Check them out:
ABAP Web Services WIKI: http://wiki.scn.sap.com/wiki/x/GYSLDQ
WS Troubleshooting Guide for Service Consumers: http://wiki.scn.sap.com/wiki/x/CIIrFQ
Cheers,
Attila