Got my Motorola ION Yesterday, not set for now.
Do not use side PTT, it seems it will trigg the DMR radio...
For screen PTT, it should work since i know few OM using it on the ION.
Can you try to disable Big PTT in dvswitch config to see what happend.
Another thing, try to reconnect to the server.
Check connect/hangup on the top of the screen