Event: Town-Hall upgrades problem

I want a trigger that does this:

E: Town-Hall upgrades to Keep
A: activate xx research for triggering player.

I can do the action no problem, but there isnt any events that says "When unit is upgraded" and "upgrade = keep", etc...

I tried "finishes construction" and it didnt seem to work..

try something like, whenver unit x enter anywhere on playavle map area

i dunno alot about triggers so i hope that helps

Edit: or you could just make the ability (if it is an ability) just require that a building be built.

Well yeah, but the main problem I am having is finding the actual tiggers..

If you can give me an exact phrase of what they are, I can do it, otherwise this is just theorying which *usually* doesnt work

-----------update-----------

heres what I have and need help with:

E: Unit- unit owned by (player 1) (finishes an upgrade)
C: (Unit-type of (triggering unit)) equal to Great Hall
A: Player- set the current research level for (Improved Gold Mining) to (1) for (Player 1)

and 2nd

E: Unit- unit owned by (player 1) (finishes an upgrade)
C: (Unit-type of (triggering unit)) equal to Stronghold
A1: Player- set the current research level for (Further Improved Gold Mining) to (1) for (Player 1)
A2: Player- set current research level for (Improved Gold mining) to (0) for (Player 1)

So the problem is this: in the condition, I need something to replace "triggering unit" to designate it to look at the "upgrading unit", however "upgrading unit" isn't an option.. There is things like "researching unit" and such, which also don't seem to work... Anyone know what I can do/use?

I know you order upgrades on building by ordering it to train a unit type so try something like:

Events:
A Unit Finishes Training a Unit

Conditions:
Unit Type of Trained unit Is Equal to Great Hall

Actions:
Your Actions here

nope, didnt work

figured it out..

problem was that before when I was using triggering unit, i had the unit type set to the base unit rather than the upgraded unit, so when i made it strong hold instead of great hall, it worked..

thanks for tips, didnt work lol, but thanks