I recently bought this device with UK TOPO 1:25 card for all of GB. On this card the UK is split into 5 tiles. I can view 3 of them fine but 2 of them will not show the 1:25 detail when I zoom in. Anything after 5km zoom level does not display on the tile for wales/west England or South Scotland. All other areas display as they should. All maps are enabled on the setup screen. if I switch the card to a different device, etrex 20x, all displays as it should. many suggestions/ideas? thanks