Cannot Enable "Activate Video" Box

When in preferences / video there is an option to "enable video".
When I click on it nothing happens. The box does not get a checkmark and it seems to ignore my request.
I have purchased the full Cross version.
I have registered my serial number on the forum.
I have downloaded the video plug-in.
I am running Win 10
Operating with Numark N4 controller
Computer vid output Bulit In + Monitor
What am I missing?
When I click on it nothing happens. The box does not get a checkmark and it seems to ignore my request.
I have purchased the full Cross version.
I have registered my serial number on the forum.
I have downloaded the video plug-in.
I am running Win 10
Operating with Numark N4 controller
Computer vid output Bulit In + Monitor
What am I missing?