In order to load the map images, you must be connected to the internet and D-RATS must be set accordingly. Further, you will want to have your latitude and longitude set in the main settings dialog (or an external GPS connected if you have one). Check the following:

1. Latitude and Longitude (or external GPS) settings
2. Internet connectivity

3. The internet toggle in D-RATS (In the File menu, make sure that Connected to internet is checked)