OziExplorer and Navman GPS sleeve ??

I have a question about the compatability of the Namvan GPS receiver and the Oziexplorer software.
I have a HP IPAQ 5400 and Navman 3450 sleeve (with Smartst software installed on PDA that I use for city driving). I have downloaded the TRIAL versions of the OziExplorer software and OziExplorer CE and have successfully installed both on my home PC and PDA. Just out of curiosity I opened the software and demo map and then connected my Navman sleeve to see if I could pick up a signal and received a "GPS SUSPENDED" message on my PDA. Does this mean that sleeve did pick up a signal but the OziExplorer software blocks it because its only a trial version, or does the Navman sleeve not work with OziExplorer. Another theory I had was that the GPS co ordinates did not "fit in" with the demo map on the screen, therefore could not give a correct position in relation to the map.

Anyway, does anyone know if I can use the Navman sleeve after paying for the full software or will I have to buy something like a bluetooth GPS receiver?

Any info would be appreciated.
Cheers,
Darren.

P.S. Anyone else run OziExplorer and GPS on a PDA set up like this???