You haven't said anything about the computer tht you are trying to hook up, hardware, etc. It could be as simple as how you are hooking it up, was it originally hooked up VGA or DVI? It may be as simple as the cable you are using. A bit more information might help. If you have both VGA and DVI capabilities, have you tried them both? If you have done this to no avail then likely it is a video failure, again, more information might help.