Particle Not Interacting with a Collision Object.

Ah, I am stumped :S.

My mesh has “Collision” enabled in the physics panel but the particles are not interacting with it.

I feel like I am missing a check box somewhere.

Below is the .blend. any help would be appreciated!

Both objects need to be on the same layer for them to interact with each other with collision. You can move an object to another layer by selecting it in object mode, hitting m and choosing the layer from the widget. After moving it, you need to rebake the sim. It is better to actually bake the sim from the particle gui, rather than just hitting alt a.