Check 1: Is the size of the print data extremely large?
Click Print Options on the Page Setup sheet on the printer driver. Then, set Prevention of Print Data Loss in the displayed dialog to On.
Check 2: Is the Page Layout Printing performed or the Binding margin function used?
When the Page Layout Printing or Binding margin function is being used, thin lines may not be printed. Follow the instructions in Check 1 or try thickening the lines in the document.