When I open a timesheet form in Acrobat 6 pro, everything looks fine. However, after I print it, a bunch of the lines dissapear from the form, and are also not present on the printed document. The linesthat disappear differ each time its printed. I tried printing on two different printers, and both documents were missing the lines. I also tried printing a different form and it worked. What could be causing the lines to disappear?