The activation code TomTom supply you will only allow the product to work on the device you registered with them.
Have you been to ttcode.com to activate your device etc ? (just an idea)
I bought full European maps in January from them and downloaded the maps, had no problems in Spain when working there. Also bought the SE USA map for £42 last month for our holiday to Orlando Florida, bloody doddle, no more juggling maps and pre-planning required. Also the POI's are fantastic, much better than the crap we have here in the UK.
Hope you get them working soon.