Windows not allowed extended display on 3rd monitor.

[maximumtech]

So, I have a 1080p monitor on DVI, 1080p monitor on HDMI->DVI converter, and a 1600x900 monitor on Mini-DP->DVI.
My computer is picking up the 1600x900 monitor, but it is refused to allow me to set it to extended display.
GFX Card: http://pcpartpicker.com/part/asus-video-card-hd7850dc22gd5v2
What is wrong with it, and how can I fix it?

 

[k1114]

That means the mini dp adapter is passive and you need an active adapter. Return it if you can, and buy an active one.
http://www.monoprice.com/Product?c_id=104&cp_id=10428&cs_id=1042802&p_id=9425&seq=1&format=2