Hi, I have a Astro 320 with a DC 50 collar. I have tried to load a full UK map that I bought with a Garmin GPS but the astro still does not display the mapping but if I load the astro onto the MAC it displays but not on the handset.

Can anyone give me any advice please? I currently have to use two GPS to check for roads etc whilst tracking injured deer. The Astro works fine apart from displaying the maps!

Thanks in advance!