Dual Keyboard Keyboard Fn F4 Does Not Work, I Don't Want Dual Screen?

Keyboard fn f4 does not work, I don't want dual screen? - dual keyboard

I want to show my monitor, which appears on the screen of my laptop, but my Fn + F4 does not seem to work, after pre-formatted.
I have tried using the dual screen of the property after the expansion into the window 2, Fn + F4 no effect, suggestions?
As with Microsoft, not mac