I am having trouble setting up a custom paper size. From 'Properties' of my Adobe PDF printer I am going to 'Printing Perferences'. Then from the 'Adobe Printing Settings' tab, I am clicking on 'Add' Adobe PDF Page Size. Then I am naming my page size and inputing the desired width and height. Next, I click on the 'Add/Modify' button. The 'Add Custom Paper Size' window closes like it has added it, but it is not in my select list. What am I doing wrong?