I bought one of the refina 16" plastics. I have lightly sanded it. After the 2nd coat picked up, I flattened it with the steel and then waited a bit and then crossed troweled the plastic over it, I am getting lines the whole way down the length of the the plastic right across the wall. i thought I went on too early so I tried it on the next wall and waited a bit longer but same thing. I was thinking maybe I sanded with with the sandpaper too coarse. I used 320 then 600 after but same thing? anyone getting this, or maybe i dont know how to use it yet!!