Had my 20oz paintball cylinder filled yesterday. Made another stop for about 45 minutes. Left the cylinder in the car. Was about 80-85 out, I left the windows open. When I got back to my car, I found the cylinder ice cold and covered in ice. I got home and attached a regulator and found it to be empty. I'm new to this whole thing, so, any help on what happened and/or what problems I have and how to address them would be appreciated. Thanks.