Dell 2300MP projector not recognizing signal from MacBook Pro OS X Mountain Lion

Our used Dell 2300MP projector connects to two of my roommates' laptops (one running Linux and the other running Windows 7) easily without having to do anything in particular. I have an Apple Mini DVI to VGA cable adapter that I've used before to connect my laptop to a TV monitor, with no problems. When attached to the projector, the computer screen flashes blue and seems to register that the projector is there, but the projector won't progress beyond "scanning signal..."

I have factory reset the projector and also pressed Option+"Detect displays" to no avail.