Try manually selecting the input in the monitor's menu just to make sure.
If it still doesn't work, does the DVI to DVI cable work on the other monitor? If so maybe the monitor and/or plug(s) are bad. Of course, another possibility with DVI is that it is trying to use analog and your monitor is digital; in that case you would need to use a DVI-D cable or force it into digital mode somehow.
A DVI-D cable has that long pin all by itself next to all the others.
A DVI-A or DVI-I has two little pins above and below that long pin.
Here's pictures of the different types:
http://www.datapro.net/images/dvi-config.jpg
Saw it posted on
this page.
DVI-D is all digital. DVI-A is only analog. DVI-I support both analog and digital.