Three monitors problem

I recently purchased three monitors for my gaming rig. I am having problems getting all three to work. I have two plugged in by DVI. The third is plugged in by a mini DisplayPort to DVI adapter. The problem is that I can only get two of the monitors working at one time. Am I doing something wrong?

What Graphics card are you using ?

I am using two Radeon 6950s. One is by HIS and the other by XFX. They are Crossfired.

Hi mcmurphy,
First, do you have all three monitors plugged into the primary card?
and secondly, unless you are using a 'Flex' version of the 6950, (or the like edition with the built in active DP) Or a display with a built in active display port. In order to support the third monitor. You need an Display port active adapter like this:
http://www.newegg.com/Product/ProductList.aspx?Submit=ENE&DEPA=0&Order=BESTMATCH&N=100006676&isNodeId=1&Description=display port active adapter&x=0&y=0
here is tutorial on setting up multi-monitor/Eyefinity
http://www.amd.com/us/products/technologies/amd-eyefinity-technology/how-to/Pages/set-up.aspx

Yes, all three monitors are plugged into the primary card. I am going to assume the adapter I have is not active (I got it from a coworker).

Thanks for the help, red!