Hello crypter,
The Knowledge Base for the Phaser 8560 says that when you empty the waste tray, the waste tray must remain out of the printer for more than 5 seconds in order for the message to clear. If you took more than 5 seconds to empty the tray and re-insert it back into the machine then we can try something else to get the message to go away for you. If you were able to empty the tray quickly and get it back into the machine within 5 seconds or less, then you should try removing the tray again and waiting for more than 5 seconds before re-inserting it into the machine. Please let me know what your status is. I will help if I can.
John
