Water level is the most important thing when it comes to automatic covers. The water in the pool supports the weight of the cover and reduces the strain when opening and closing it. If the water level is below the skimmers you're putting a lot of pressure on the track, ropes, and motor, which can cause the cover to not operate correctly. Just as important as the water below is the water on top of the cover. Anytime your cover is closed you should have a cover pump laying on top. If too much water collects on top of the cover it pulls the cover down once again adding strain to the track, ropes, and motor. Too much water on top of the cover or not enough underneath can both cause the cover not to open.