Printer Cannot Print A3 (Print Blank)

3 Things Causes this Problem

1. improper stettings of paper size.
2. dirty line sensor,(sensor with light)also called media sensor located on the right side of the catridge carriage unit,clean it from the from downside ,(from the point where light comes) with a cotton bud.
3. faulty flex cable ,connected from logic board to catridge carriage unit.