Change a material using buttons from HUD

I have no idea why this confuses me so much but here we go…
I have a planet with lightning effects on the material and all I want to do is have a button in the HUD toggle the effect. I think I have set up the dynamic material correctly but I’m not sure to be honest.

Any help at all would be great!
Cheers guys!

Have a look at the screenshots below

This is my attempt at creating a dynamic mat.^

This is my HUD (it appears in the game just fine)^

The material editor window for the master material that I’m using^

A close up of the lightning material that I need to toggle off and on^

HI!

This is several tutorials about the changing of materials using UMG:

https://www.youtube.com/watch?v=wE5hhAeWJUw