Gui Machine - No systems returned

I have loaded the GUI Machine onto our dev server and verified the installation.. I have also configured single sign on to our dev SAP system from the PORTAL EP5SP6 but when I try and access the SAP systems through the GUI Machine I get a login box in which I enter my username/password and click ok, I don?t get any error messages and the ?No Systems Available? message does not change

Any Ideas? do I have to have specific parameters in the systems.xml /jcodestinations.xml files to get the GUI Machine to recognise these systems?

Thanks in advance

Kev