Dell FP2405 - Problems with Dual input and display (PBP)

PLease could anyone help.

 

I have taken delivery of a 2405 of which the display is stunning. I use a ATI Asus X700 PCI Express video card. However in setting the system up for dual PBP side by side viewing I just cannot get this to work. A friendly techy who really knows his stuff has struggled for ages. Both monitors, both inputs have been set up and selected on but the VGA display will show nothing.

 

Anyone have any ideas as to what may be the problem? The driver from ASUS is the latest and they say the card WILL support PBP.

 

Appreciate anyones suggestions. THanks.