I've recently bought this HP LaserJet Pro MFP M26nw and some problem occur when I want to print PDF file with manual duplex.   For example, I usually print four pages/slides of PDF on one A4 page. What should happen would be slide 1-4 on page one of the print-out, then 5-8 on the back of the same A4 paper. Similar problems occur even if I print one page of pdf per page of A4.   However, when I use my printer, it prints 1-4 on the first side while 5-8 on another sheet of paper. Eventually it will be the last 4 slides on the back of the first sheet of A4 paper. This problem doesn't occur when I print the same way on Microsoft Word. May I know how to fix this problem? Thank you