Lej-640 Won't Set Up 1/2" Material?

[petepaz]

roland LEJ-640 uv hybrid flatbed printer. supposed to be able to print up to 1/2" thick material. we have had the machine for years and i think this is the first time trying to print on material this thick. i have the head on high setting and the manual dimensional setting up to .510 (highest it will go) and it won't set up the material.
anyone ever had this issue and or know how to make it work?