Spawn object visibility in multiplayer

Hi all,
I try to learn how to build simple multiplayer game.
For now, with my project, i can create a session with some players on the same map, shoot, kill each other and spawn again randomly. When a player is killed, he disapears for others player with a multicast custom event (visibility node).
It works playing throught Steam serv.
There is something i don’t understand. I try to spawn randomly a BP actor (cube) with the level blueprint. It works but the cube is only visible by server. I kwow that the cube is also present for clients (there are collisions) but not visible.
I try to put the visibility in a multicast custom event, as i did for the character mesh when he died.
But i get an error.
How can i create a random actor spawn on my map whitch is visible by server and clients?

Thx a lot.