Hi guys just a noob here. Ive had a lot of (noob) issues with collision and trigger events.
Most of them I think resulted, like Alex says above, from bad setup of rigid bodies and colliders.
I have now started adding a rigid body and a collider to every game object (the collider and the collidee) involved in the trigger/collision event. This seems to work well...
Although im pretty sure playmaker warns that the object requires either a rigid body or collider when adding a collision/trigger event- from my (noob) experience they actually need both to send the events (or maybe im wrong, but it seems to work like this so yeah...).