I was driving in a parking lot. I failed to yield to a car moving from my left to right on the main way, and we had a collision at the intersection. HOWEVER, the car came in the parking lot through a "DO NOT ENTER" sign, which is not far from the accident location. I was sure there was no other moving car in the parking lot before he came in. Now Geico said it is totally my fault, (maybe) partly because I have never had an accident before and do not know how to argue. On the other hand, the other party sent them tons of photos supporting their version of the story. Before I do more, I would like to hear your advice, is the other driver at fault too?