You can’t play animations to the client on the server. You should use :FireClient() inside that code, or just play it in a local script right after it’s fired
edit: You also used
game.Players.LocalPlayer
Inside a server script, when you had “player” as a parameter.
Another thing, I don’t know if your format for AnimationId works. It might but if it doesn’t use “rbxassetid://”…animationID
Simply put that code into the script for your gui mouse click, simple as that! It will replicate to the other clients no problem as long as the game owner or group owns the animation.
Could you post exactly how you figured it out so that others with the same problem can reference your solution? It’s not in good taste to just say “figured it out” and then mark that as the solution because it’s not a proper solution and leaves no reference for how others can fix their own similar issues.