Training Structure - Need a hamd here!

[TTFTCUTS]

Is there any way at all of finding which structure trained a unit after a "Unit finishes training" event?
I've tried using triggering unit with no success, and was wondering if there is actually a way that works, or if it simply can't be done.

 

[PEONMASTER]

OK…i take it you want to do an action to the building that trained the unit, so heres the trigger i would suggest:
Events
Unit - A unit Finishes training a unit
Actions
Unit - Explode (Triggering unit)

Where it says explode, you substitute that with whatever action you want. Seems preety simple, am i missing something?
Hope this helps.