Laptop won't recognise monitor via hdmi

[Karldahemster]

I have a lenova Yoga 460 i7 6500U with a gt 940m
When I connect the hdmi cord to the monitor nothing is recognised. I have also tried it on various other monitors and my TV. Nothing works. These other devices work fine with my other laptop/pcs.

 

[Phillip Corcoran]

Try pressing F7 on the laptop to switch over from built-in screen to external screen.

 

[Karldahemster]

Try pressing F7 on the laptop to switch over from built-in screen to external screen.

No change monitor says check cable connection its a philips 247E 24inh