Congrats and condolences then!
Either the burn was bad (the failure to verify), in which case, a reburn might fix it, or you have a navigation problem, in which case you need to fix that.
Can you navigate by menu to the special features? Is the end action of the timeline for the main movie clearly set to the special features menu? In Encore preview, in the main timeline, click the "end action" icon; does that work correctly?
You can also try to play the image, to see if it behaves correctly (again pointing to a bad burn). The problem with that is that a) you generally have to mount the image and b) some software players don't emulate correctly and a failure doesn't mean much. But if it did play correctly, it points to a bad burn.
What third party burning software failed?