FireClient not working inside ServerScriptService?

I have two scripts. A local one and a server one The server one is inside the ServerScriptService The client one is inside the StarterGui.

--server script. its not the entire script.
player.Chatted:Connect(function(text)
			print(dummyCount)
			local chattext = string.lower(text)
			if chattext == "/createdummy" or chattext == "/cd" then
				if dummyCount < 4 then
					local clonedDummy = dummy:Clone()
					clonedDummy.Parent = folderPerPlayer
					clonedDummy.Name = player.Name.." Dummy "..dummyCount
					clonedDummy:MoveTo(humanoidRootPart.Position + Vector3.new(math.random(-10, 13), 7, math.random(-9, 12)))
				elseif dummyCount == 4 then
					print(player.Name)
					getWarning:FireClient(player, "(You can only see this!) You can't add anymore dummies! Use /removedummy (/rd) to delete all dummies!") --it wont fire
				end
			end

<><><><><><><><><><><><><><><><><>

--client script, full script. wont print message.
local starterGui = game:GetService("StarterGui")
local replicatedStorage = game:GetService("ReplicatedStorage")
local getWarning = replicatedStorage:WaitForChild("getWarning")

local function CreateSystemMessage(message, color, font, fontsize)
	starterGui:SetCore("ChatMakeSystemMessage",{
		Text = message;
		Color = color;
		Font = font;
		FontSize = fontsize;
	})
end

while true do
	CreateSystemMessage(
		"{System} Chat /createdummy (/cd) to spawn dummies and /removedummy (/rd) to remove dummies.",
		Color3.fromRGB(252, 165, 3), 
		Enum.Font.FredokaOne,
		56
	)
	wait(420)
end

getWarning.OnClientEvent:Connect(function(message)
	print(message) -- wont print?
end)

--[[
CreateSystemMessage(
	message,
	Color3.fromRGB(255, 115, 115),
	Enum.Font.FredokaOne,
	56
)
]]