I bought a TomTom GO 920T and, inside the TomTom box, I found a "Free maps for 1 year" code. I tried to enter the 10-character code that was included on the Maps leaflet in my TomTom GO 920T packaging on the web site www.tomtom.com/1yearmaps, but I receive a message that the promotion code I entered is invalid. Can you help me?