I actually had the same problem once. I thought it was because I haven't bought the password for Pepakura Designer, but I've been able to print out other things that I've modified on designer. It seems to be an intermitten problem. Now, before I print anything on cardstock, I run a single sheet of 20lb paper to see if it prints ok, then I use that piece of 20lb paper to lay down on my workspace to keep glue from getting on my table.