My back wheel locked on me. My emergency brake was not on, as far as I could tell. I thought maybe it was a transmission problems since my fluid level was low and I could not move forward or backward. I added some and tried to backup and that was when I saw my back right tire was dragging and not rolling forward or backward. After I tried to lock and release the emergency brake bar several times, and after letting the transmission fluid go into the engine for for 15 minutes, the car moved fine and the wheel unlocked. Can you tell me why a wheel would lock?