Hi,
I can't find any errors, please double check the following:
-- you have the "PlayMaker Unity 2D" prefab instanciated in your scene
-- you have a "PlayMaker Unity 2D proxy" component attached to your GameObject you want to receive the collision event from.
-- you have a rigidbody 2d and a collider 2d properly setup on both objects colliding.
Let me know how it goes,
Bye,
Jean