TOMTOM 5 "No GPS Device"

I have a Navman se 3000 GPS jacket which worked fine with Tom Tom 2 & 3. Now I have upgraded to TomTom 5, I cannot configure it to the right Com Port at all. when I run my very old Navman software it finds the GPS Jacket on Com 7, but only Com 3 & 6 appear in the TT5 config list.
Tried connecting on "NavMan GPS", first option, but nothing works, just get "No GPS Device!" all the time
What can I do? and what baud rate should it be set to ?
I have asked TomTom two days ago and so far have had NO response.
thanks in Desperation
Andrew