I am unable to use the new retinal display with the 600 series smart board

I am a teacher and have both an older macbookpro (2006 2gigs ram 10.7) and the new retinal display macbookpro (10.8.2). My school had two versions of smartboards (one is the 685 with a UX60 projector; the other is a newer 800 series). My older macbookpro works with both boards but my new macbookpro works only with the newer 800 series. It does not show any display at all with the older boards. I have tried reducing the resolution but that does not help. I have taken it to apple and it checks out fine. I have spent hours with smartboard support in Calgary. They can't figure it out but have never used a Mac with a retinal display and the older board or the UX60. Any suggestions?

Thanks,

Ed S