external display issue

hi all.i would like to hook my macbook to my desktop monitor.so far i purchased a wireless keyboard and the mini dvi to dvi cable.i didn't realise that i needed a male dvi end to go into the monitor so i got one of those.nothing happens however when i make all the connections.i should note that the short mini dvi adaptor is made by dynex and not apple,is this the problem?or is it a seting issue on either my macbook or the lcd monitor?
thanks in advance for any advice.

 

thanks for the response.no,nothing comes up at all.i don't see any switches on the monitor that need to be moved.not sure if it can remain hooked up to the pc at the same time.