dual layer dvd burned but won't playback

hey there

I just burned a dual layer DVD in DVD Studio Pro (its an HD wedding - all settings done as directed)
It will not play back in the DVD player on my iMac (OS Lion)

I tried to playback on my older machine running Tiger and all works just fine. The Lion machine says it doesn't support the disc?

I also attempted a playback on my xbox 360 and I get a "multi media disc" setting. I can't 'play' the disc.

Any thoughts??

Not had this issues in the past.

Thanks,
enero