At my school I am a student sound/lighting technician. We have a mac pro that has two mini display ports and a dvi port. We use a video switcher that has a dvi in and out that sends the video to our projector. Today we are running a slideshow for our music camp but we have a problem. Our video switcher for some reason doesnt like mini display port. When we send a dvi signal from mac pro>mini display to dvi adaptor>dvi cable>video switcher we dont get a signal. When we send it mac pro dvi out>dvi cable> to video switcher it works. We use the dvi out for our monitor so we are trying to use the mini display for our projector. Also, we used a macbook pro to send the same signal, macbook pro>mini display to dvi adaptor>dvi cable> video switcher and it doesnt see the signal. so basically, when we use a mini display to dvi adaptor it doesnt get a signal but when we use just a dvi out it works. the computers dont recognize the projector when we use mini display either. any ideas. EDIT: could this because we need a dual link adaptor.