Tower stopping before it's even started building

[En_Fuego]

Okay, so I have a TD I'm making and for some reason all of a sudden, the towers stop building before they even start! So if you could imagine, you go to build the tower and everything's fine, then when it starts to build, it stops instantly and the un-finished building sits there with "( )" for the process bar.

Any ideas on what I should do to fix this?

 

[Ghan_04]

Change the builder unit's race to Undead.

 

[En_Fuego]

Wow, I can't believe made such a stupid mistake as to not place the worker as Undead.

Thank you very much.