I am using Illustrator CS5.1 with a Mac and a Canon pro-100 printer. Every time I try to print a custom size (for ex. a 4.5 x 6.25/A6 card) the "Custom Size" setting is greyed out. If I go to page set-up and change it there, it will pull the paper through the printer but prints nothing. I have re-installed the drivers, called Adobe and Canon and am getting nowhere.