Learning abilities through item purchase

[Prince Panda]

Okay, I'm trying to make units learn abilities, but here's the problem: they're not heroes (Is that a big issue?)

Here's a really simple trigger I'm trying to use:

Events -
A Unit Uses an Item

Actions -
IF (Item-type of (Item being manipulated)) Equal to Freezing Arrow) then do (Unit - Add Freezing Arrows to (Hero manipulating item)) else do (Do nothing).

NOTES:
1. Freezing Arrow(item) and Freezing Arrows(ability) are different
Freezing Arrow works like Tome of Power (It is diminished when bought, but has no effect).
What I'm trying to do is make a regular unit buy an item and make it learn an ability by doing so. My problem is, the item functions are only provided for heroes.

So far, this trigger is not working.
Help, thanks.

 

[Diablo-dk]

im not 100% sure if the trigger is fired on the event A unit uses an item, try Event - A unit Aquires an item or purchases an item.

 

[Prince Panda]

There are no actions relating to the purchase of an item though.
EDIT: err nevermind, this worked somehow, thanks alot ^_^