Homogeneous Multi-adapter video driver




I have developed device driver for window xp based on microsoft provided sample source code.
The driver works fine for one card but when i connect more than one card ,then one card shows the display and other doesnot show anything.

My requirement is to have more than one card of same type on PCI slots and use same driver for all the video adapaters.

Could you suggest me ,what are the specific changes i have to make, so that the driver should work for all the video adapaters?

Thanks in Advance

Best Regards