We are new owners of a used Atlantic oval 12x24 pool. We were installing the liner and it had a nice over lap all the way around u till we started to fill it. Then at one end it kept falling off And appeared now too short? We are u sure what to do or why it's happening? We have put a halt on finishing it as it's been cold so we only put enough wTer in it to support the walls to prevent it fr being blown in and buckled. What is wrong? Why is the liner doing this?