MDP to MDP not working

[CustomSurfaceP2]

I know there's some threads about this already, but have not found a solution to the problem. I bought a monoprice mini display port to mini display port cable to try to connect my SP3 to my 2009 iMac 27inch so I can do some photo editing but when I plug the cable in it the iMac just shows a black screen. After several seconds it reverts back to it's default OSX desktop. Is there something I have to enable to get the screen to mirror over or extend over? Or is it something I have to enable on my iMac? I thought it was plug and play.

 

[malberttoo]

If that iMac (I'm no Mac guy, just looked up the image on Google images) is an all-in-one computer... then probably it can't be used as an external monitor. The DisplayPort on it is probably an out, not an in.

 

[CustomSurfaceP2]

It's both ways as of 2009 Late models, just not sure why the screen blacks out, maybe it's the cable I'm using?

 

[kundas1]

sounds like it might be the cable... sometimes these cheap cables can't handle the through put...

 

[wertzius]

Did you use Command-F2 to activate the Target-Display-Mode on the IMac?