credit

I don't understand banks. I am trying to get a loan to buy a house but I keep getting turned down because I don't have enough credit built up. If nobody will give you a loan how are you supposed to get credit? I had purchased a house before and had to sell it because I moved up here, so why doesn't that count. I had a car loan paid it off, ended up trading that in for a new van. I got a loan for that but can't get one for a house. It is very frustrating. I just needed to vent, thank you for listening.