4 displays on a ATI HD 7950

I have an ATI 7950, I built the PC around the graphics card, I need to extend the desktop across 4 displays. I can display across 3 displays with no issue, however whenever I try to add the 4th monitor, ATI CCC tells me that I must disable one of the other displays before continueing.

the three primary displays are all Samsung SyncMaster S24B30BL, all operating at the same resolution
the 4th Display is a Dell 1905FP

the card (7950) has the following outputs: DVI, HDMI, 2 mini display

the cables/dongles I am using are as follows: DVI to DVI, HDMI to DVI, MiniDisplay to DVI (passive), MiniDisplay to DVI (active)

I have shifted the connections around, and tried numerous configurations with the above cabling and monitors, any 3 monitors with any 3 of those cables will work just fine, but not with 4, the software simply refuses to activate the 4th monitor.

Also I have read other forums of users running 4 displays on this same card with no issue, I have sent PM's to them asking what their connection setup is, but I haven't got any replies and this project is on a deadline, and I am running out of time