Client can't trigger CustomEvent which has Run on Server?

As the title says,
I had read the tutorial from Epic on Youtube about “Replication”.
The true is , I want to make a Multi Player game with Building system ,so I’m learning about how to replicate to Server.

as i tried to follow the video, or another tutorial . I always got failed.

My conclusion is : Maybe the Client can’t trigger the CustomEvent which has “Run on Server”?
cause my client always can’t pass through the node.

PLZ don’t mind about the node(SpawnActor from class), it doesn’t work as well btw.
Is there any Idea?