Hi,
All is fine, I think you just forgot to add a rigidbody to one of the two gameobject interacting together.
What are you using as a gameobject to move inside your trigger? if you use a dummy cube or something, it has to have:
-- a Collider ( set as a trigger or not)
-- a Rigidbody
and your trigger GameObject must have at least a Collider set to is trigger
I am not too sure how you have setup your script to work in the exact same situation that the one above, but double check indeed.
Bye,
Jean