In order for this DVI to VGA adapter to operate correctly in your setup, make sure that the following is true:
The video source is DVI-I or DVI-A (analog signals must be present).
The video destination is VGA.
DVI to VGA adapter cables are passive and simply use the pins from a DVI-I source to convert to VGA.
If you are using a DVI-D source and want to convert to VGA, you need an active adapter, such as the DVI2VGAE. You can find more DVI-D adapters at http://www.startech.com/AV/Converters/Video/.
Note: The analog VGA signal (DVI-A) must be present on the DVI-I interface. Some DVI-I receptacles may have all 29 pins for DVI-I, but only have a DVI-D signal present. To determine what type of DVI port you have, refer to http://www.startech.com/faq//video_signal_converters_dvi_interface.