Dell U2715H not connecting to Imac

[bgsnmky]

I have an iMac late 2012 model.
Mac OS Sierra

I jut received my new Dell U2715H monitor last night and have called dell 4 times. No help.

I am connecting via the DP (on monitor) and then on the mini DP on the iMac.

It is not connecting or recognizing it at all.
(i have had previous external monitor and all works fine. Even still have one external connected now and this will be my third - just replacing older 3rd monitor).

I am sure it is the connectivity and how I am doing it.

Does anyone know if the DP to miniDp should work. The research I am finding seems like it should.

 

[DFWHD]

okay, stupid question here, but are you setting the input to the DP setting on the Dell? I've got the same monitor and it does not automatically switch to the input with the signal. I have to manually switch it using the buttons.

 

[Doug Hope]

Are you sure you don't have it plugged into the output display port?