My Toyota Camry 1998 has an automatic transmission which I have recently replaced. My uncle rebuilt the newer one and I even bought a new solenoid for it. But now everything works... until I try to reverse. At first we thought the brakes were froze. But we've checked and they aren't. No matter how much pressure we put on the gas pedal while it's in reverse, it still doesn't move. What could cause this and how could I fix it?