Problem with multiple Techtree Requirements

Problem with multiple Techtree Requirements

I have an upgrade, and I would like it to have more than one requirement, but I can't get it to work properly.

The problem is that when all requirements are met, the upgrade is still unavaiable for research.

The requirements are:
Mithril Plating (did the Req. level properly)
Class 1 Territory (building)
Nether Gate (building)

I tested using only Mithril plating, and I tested using only the two buildings, and in both cases it worked. It just won't work together.

Thoughts?

*Bump*

sometimes warcraft is just picky. maybe completely recreate the upgrade from a different base upgrade but have it do the same things.