Oki MPS420b User Manual page 41

9. Close the Paper Tray and press the Online button. The message window should
disappear from your screen and the printer finishes printing the remaining pages of
your document.
Note
You must press the Online button to start the printing for the other side. The
default time is set to one minute, failing which, the data is deleted and not
printed.
2-Sided (Duplex) Printing > 41