You need to make settings on the printer to use the Staple Finisher when copying.
Select in the following order.
If you select Auto, the printout destination is set to the finisher tray. However, this may be set to the output tray, face down tray, or the top output tray depending on the paper size or the paper type.
When using the finisher tray, do not remove your printouts while the print job is still in progress. The print position may be misaligned and the staple position may move from its original position.