Chat thing not working?

I'm not sure why this isnt working, im trying to make it so it says "Hello [Players name]!" but its not doing anything.

local Chat = chat("Hi there "..plr.Name..'!', Color3.new(0,0,0))

local function chat(text, color)
game:GetService('StarterGui'):SetCore('ChatMakeSystemMessage', {
Text = text;
Color = color;
Font = Enum.Font.SourceSansItalic;
FontSize = Enum.FontSize.Size18;


}
end



game.Players.PlayerAdded:connect(function(plr)
chat()
end)