OK I have an 8GB SD card installed and formatted in my Via 1535. I load the Canada and Eastern USA maps on the device using MyDrive , all OK so far. It asks me to select the active map from the list (only Canada and eastern USA shows) no problem. I then go and load the Canada and Western USA map this also goes OK but it seems that it overwrites the Eastern map and it is the only map shown in the active map selection list. Can I have the two maps loaded and then just select one or the other as active? If so how to do it and if not what is the use of the SD card ?????