My TomTom GO50 does not show as a device when plugged into my iMac. The computer software is up to date as is the device, I use the original USB cable and have tried all the USB sockets on the iMac. It connects to MyDrive Connect and I am able to update and also send new routes on the route planner. I have checked that 'external discs' has been ticked in Finder preferences. I have also reset the device to no avail. I have been on the TomTom website and sent a message asking for help but have not heard from them. The TomTom is approx 2 years old but this is the first time I tried to add POI's so had never noticed this problem. Any help will be appreciated.