I think the problem is that the original chainring is about 3mm thick where it bolts to the crank arm and the BBB one is 4.5mm. Below is a photo showing the gap where the chainring will not sit flush against the mounting points, and a diagram attempting to explain where the problem is.
I've had a look at Campy tech docs and can't find anywhere specifying the width of the chainrings at that point. I assume the BBB one just isn't compatible. Or have I missed something?