DVDO iScan Duo and Mac Mini

I connected my Mac Mini to HDMI-2 of my DVDO iScan Duo, but when I select the HDMI-2 output the screen is blank. The output of HDMI-1, connected to a DirecTV HD-DVR, works fine, and the Mac Mini connected directly to the TV via HDMI also works fine. Does the iScan Duo not pass output from a computer?

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I set the display to 1080p, but I'll check for a video setting.
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