LG 27MB85R-B will not turn on with Mac coected

I was setting up an LG LG 27MB85R-B 27" monitor at a desk and after I plugged in all of the cables and plugged the Mini-DP into my macbook. I tapped the touch sensitive power button and... nothing. I rechecked all of my cables to make sure I didn't miss anything but everything was right. At this point I don't know what's wrong! Help!