Mirroring not working
 

I am using DisplayLInk for Mac on a Hackintosh running Sierra 10.12.5 and I am unable to enable mirroring with three monitors. I have a display connected to the onboard DVI port and one to the onboard HDMI port and the third one to the HDMI port of the DisplayLInk. The computer has no graphics card added. The computer does see all three monitors but mirroring does not work on any display.

I guess there is a special manner to hook the three displays that I cannot figure out.

Help, please!