How long are you waiting after printing the film to tape it to the screen and expose? I have an epson 3000 and if I don't wait 5 or 10 minutes then the film sticks to the screen when I pull it off after burning.
Alas, if you mirror the image, you will expose through the 5 mil polyester backing film and your image will get choked. If you have multiple lamps, it will choke more.Did you try and mirror your image....cost $0.00