Problems with Tom Tom 3 and Seidio Mount

Can anyone help, I have just purchaced a Seidio 2500 powered mount for my Axim X3. When I use the new mount Tom Tom appears to get no signal from the gps receiver, other programs (GPS Dash and Winfast Navigator) both connect to the receiver on COM1 with no problems. If I switch back to the original y cable Tom Tom works fine, as do GPS Dash and Winfast Navigator.

I assume it something in the set up Tom Tom so I have tried installing TT GPS Driver 2.07, but the problem is still there,

Any ideas would be gratefully received