hello to every1 from the uk and help neede

[dobermann1956]

i have a tt920t version 8.351 which has just been updated, my problem is that i managed to download a tt map of brazil which is 835 2366 i unzipped the file and transfered it on a 2gb sd card, i put the sd card into the tt and it regognised the sd as brazil, but when i tried to get into the brazil map an on screen message came on telling me YOU CANNOT USE THIS MAP ON THIS DEVICE: BRAZIL 57.
COULD ANY1 OUT THERE PLEASE HELP ME WITH ANY SUGGESTIONS AS TO WHAT I NEED TO DO TO MAKE THIS MAP WORK ON MY TT920T......MANY THANKS TO ALL IN ANTICIPATION OF YOUR HELP.....Dean in the UK