P2414H DP in, does not see laptop HDMI out

My company was closing an office and they had a bunch of monitors that they were going to give away or throw out. So I brought one home for my son's laptop. This model has three types of outputs: VGA, DVI-D, and DP (Display Port). We have three laptops in our house, all of which have only an HDMI jack for an external display.

So, I purchased a DP to HDMI cable. But when I plug it in to the monitor and laptop, the monitor says that it sees no signal from the PC and the PC says it doesn't recognize an external monitor. I have tried both the Display Port and Auto settings on the monitor, but with no luck. I have also tested with all three laptops, two of which are Windows 10 and one of which is Windows 7. Since I get a message on the monitor about lack of signal, I am presuming that monitor itself is working correctly.

Of course, there is always the possibility that there is something wrong with the cable, but is there anything else that might be the cause?

If it is the cable, I am wondering if I should instead try a VGA to HDMI cable instead - perhaps that would be more like to work?