Display Port and DVI Distribution amp

I am trying to output DVI from a New MacMini, using the Mini DisplayPort, to a series of DVI distribution amplifiers. The signal in this setup, ultimately needs to be distributed to sixteen LCDs in a video wall. I have attempted this setup using Gefen EXT-DVI-144N 1x4 DAs. With the New MacMini and Mini DisplayPort as the source I can only get a picture from the first output of the first DA. All other outputs give me a “snowy” picture. If I use an older model MacMini with the standard DVI connector, the system works fine. I would simply use the older Macs I have for the project but they will not run the ProVideoPlayer software I plan to use for syncing several of the MacMinis. From discussions with Apple and Gefen it appears to be a Digital rights management (DRM) issue. Since no protected or copy righted content is being used it is unclear to me why DRM would come into play. Any insight to the problem would be appreciated.