Stop AI from building ... (too long to explain in title)

[Duwenbasden]

I have this building (Nether Altar) that upgrades to a second tier hall (High Altar), but whenever the AI is order to upgrade the Nether Altar, it will somehow build another Nether Altar; if they upgrade the High Altar to the last tier, they will upgrade the Nether Altar into a High Altar and build a third Nether Altar! Why is this happening, and how do I fix it?

 

[AceHart]

Is that altar already on the map? Or do they construct it first?

> whenever the AI is ordered to upgrade

AI script from the AI Editor or through some "order" trigger?

 

[Duwenbasden]

All from AI editor, no triggers.

The Altar is a replacement of the first Town Hall.

 

[AceHart]

Do you have a normal altar in your build list before the actual upgrade order?

 

[Duwenbasden]

Yes, it is the first item in the training list, followed by 5 workers.

and also the towers that can be upgraded seem to have the same problem (building two, upgrading the two, and building two more but never upgrade)