Either its added the wrong way or its the wrong paper, it could also be the settings on the machine, if you try to print a4 and the bypass tray is set to a5 etc, this message will come up.
If you put the paper in with the shortedge/longedge first and you selected landscape/portrait, this will also generate the same message.
On a WorkCenter 7120 i get the error message "075-451 Tray 5 is empty. Add paper to Tray 5. Printing can continue." Everytime I try to print over the network. Both tray 1 and Tray 2 are full of paper. Tray 5 is the pull down tray on the side. Please Help.