Sphere Collision not working in my blueprint

I’m following this tutorial:

The tutorial is called Adding Networked Features to 3rd Person Template - Part 2

My bomb keeps falling through the floor. I don’t understand what I’m doing wrong. The tutorial is for a previous version of UE4, so maybe that is part of the problem. It’s the first 5 mins of the video where I have the problem.

Any ideas?

I think if you drag your collision or bomb component as root it should start working, the comments in the youtube video should also mention something about that