Problems Printing on Corrugated Plastic

I just started in the screen printing business. I've been in offset printing for 30 years, and Vinyl sign making for 10 years. I've successfully printed t-shirts, but am having difficulty with cor-plas. The substrate wants to stick to the screen and the flutes show though the ink. I've used 200 and 305 mesh screens. the 200 seems to lay the ink better, but with both screens, I get what looks to be extra ink around the letters. I'm behind the 8 ball pretty bad here. It's saturday and I need to do 100 of them by monday. Help Please!