[Spell] Tower do not spell

[wcity]

Why is the tower not use spell? in my other map Ice Fortress the unit cast so many magic but in this map even if I give mana to tower and spell is easy low mana and cooldown they don't use it?

Also some creep do not crit on tower but crit is already air enemy ground why is not working?
http://www.hiveworkshop.com/forums/map-development-202/siege-castle-defense-265990/

 

[Flux]

Depends on what spell you based it.
More info here