U2715H not recognized with imac late 2012 or macbook pro

[bgsnmky]

just unboxed my new monitor yesterday.  

I tried using the DP  and Mini DP cable and i just keep getting the No mDp or No Dp.

This is attached to my imac late 2012 with Mac Sierra.

HELP!

I called Dell - 4times yesterday within 1/2 hour.  I got transferred 4 times back and forth to wrong departments and disconnected twice.  One of the worse experiences I have ever had. Honestly almost enough to return the monitor!  IS this typical.

[bgsnmky]

should I be able to use the supplied calbes the Dp on the monitor to mini port on mac

[DELL-Chris M]

Working via private message.