How to change collision of my landscape with blueprint? (4.18)

Hello,
Everything is in the question but I’ll explain it:
So, at the beginning I have a landscape (which represent the sea) and the character can’t walk on it, this is quite simple I just set the collision preset to “NoCollision”.
But, later in the game you get an object which allow you to walk on water. And here is the problem, I put a “Set Actor Enable Collision” node (because it’s the only thing I saw with Set and Collision in his name) and it doesn’t work.
If I check the case, we can walk on water even at the beginnign of the game when you don’t have the object which allows you to do it. If I doesn’t check the case, we can never walk on water, even with the object.
I hope you understand whath I’m trying to say, my english is quite bad I’m French^^
Have a good day

If you use console command fly it gives the appearance of walking on water. Usually you keep walking on the same level with that command if you don’t add any fly capability in movement settings.

Just a thought.