A couple of possibilities. If the DVI/SVGA you are attaching to is a DVI-D or Dual Link, even if you have the adapter it isn't going to work. Here is an image:http://www.talktoanit.com/A+/aplus-website/images/connectors-dvi.jpg
Other possibility is if you are trying to hook it up to a DVI-I port, which would work with an SVGA monitor but you have a DVI-D connector on your adapter.
Either of these seem to be the issue?