Why can't I edit the fontsize of game messages sent to the chat system?

So I’m working on a system that will send messages to the server, and will show them globally (or individually) via the chat system; this will send alerts as to teamkilling, capturing different points in the game, killfeed, etc.

It works fine, I can alter the text’s color and the content of the text, but I can’t edit its size no matter what I do. How do I fix this?

Here’s the code:

---- server sided script, sends message to the server via a remote
local notif = game.ReplicatedStorage:WaitForChild("Remote"):WaitForChild("SystemMessage")

notif:FireClient(killer,"[WARNING]: Teamkilling will get you kicked from the game!",Enum.FontSize.Size10,Color3.fromRGB(241,43,53))

---- this script is triggered by remote firing and sends chat messages.
game.ReplicatedStorage.Remote.SystemMessage.OnClientEvent:connect(function(txt,size,color)
	game.StarterGui:SetCore("ChatMakeSystemMessage", {
		Color = color;
		Font = Enum.Font.ArialBold; 
		FontSize = size; 
		Text = txt;
	})
end)

Hello! Make sure your argument is an Enum.FontSize,

Here’s a list of sizes you can use to update the font size:
https://developer.roblox.com/en-us/api-reference/enum/FontSize

for example:

Enum.FontSize.Size14

Enum.FontSize.Size10 is one of the arguments in my remote firing event.

Does it show any errors?

If no, try to rename the variable “size” to a different one, due to the fact that “Size” can be member of many things.

No errors, and changing the name did not yield anything new.