Sounds like your ram is inserted incorrectly. You should remove it then put it back. You can do this by inscrewing the two screws from the middle panel, and the ram will be one or two cards about 3 1/2 inches long. Push off the clips on both sides of the ram, then tilt up and pull out. If it is put in incorrectly, removing may take some effort.
Once removed, put back in by firmly pressing in to the slot at about a 45° angle, then tilt down till the clips clip on. I hope this helps. If it doesn't, I can put a video in to show you how to do it.