Why dosen't this server script recognize PlayerGUI?

So i have this server script called "Game Script" in ServerScriptService but it dosen't recognize PlayerGUI, well if i click on the play button it works but not if i upload the game and play or test the game with 2 players on studio, It's nothing wrong with the plr it's when i test with 2 players on studio then when i go the the Players tab and then on one of the players playerGUI is there but not the guis

Here's the script:

function pMsg(text, t, plr, color)
	if plr ~= nil then
		if plr:findFirstChild("PlayerGui") then
			if plr.PlayerGui:findFirstChild("Main") then
				if plr.PlayerGui.Main:findFirstChild("Message") then
					if color == "Red" then
					plr.PlayerGui.Main.Message.TextColor3 = Color3.new(255/255, 0, 0)	
					elseif color == "Green" then
					plr.PlayerGui.Main.Message.TextColor3 = Color3.new(85/255, 255/255, 0)
					elseif color == "Orange" then
					plr.PlayerGui.Main.Message.TextColor3 = Color3.new(255/255, 170/255, 0)						
					else
					plr.PlayerGui.Main.Message.TextColor3 = Color3.new(255/255, 255/255, 255/255)			
					end
				plr.PlayerGui.Main.Message.Text = text	
				end
			end
		end
	end
	coroutine.resume(coroutine.create(function()
	wait(t)
		if plr ~= nil then
			if plr:findFirstChild("PlayerGui") then
				if plr.PlayerGui:findFirstChild("Main") then
					if plr.PlayerGui.Main:findFirstChild("Message") then
					plr.PlayerGui.Main.Message.Text = ""	
					end
				end
			end
		end	
	end))	
end