Hello, my name is amie

Question

Hello, my name is amie and I currently jsut started a screen printing company and we are having serious issues with Coral Draw and getting our artwork to print right. We change the letter size to 13x19 for our film positive size. Then when we go to print our films on our epson 1400 and we use a power rip program it is never in the right position according to what it shows on the print preview. Help.