I downloaded all the maps available for my states but when i click them in base camp there is no display. I have one that shows a few dots here and there and some show nothing.
I have tried installing several of them again but the same effect occurs.
Have you read http://www.gpsfiledepot.com/tutorials/how-to-open-maps-in-garmin-basecamp/ ?
I think my problem is that i didn't zoom in enough or that I am on Basic Map Mode (check View->Basic Map