Why does it say nil value everytime?

In a localscript in a gui in startergui:

plr = game.Players.LocalPlayer game.Workspace:WaitForChild("TestFunction"):InvokeServer(game.Players:WaitForChild(plr.Name).PlayerGui.ScreenGui:WaitForChild("TestLabel"))

In a script in workspace:

local eventc = Instance.new("RemoteFunction") eventc.Parent = game.Workspace eventc.Name = "TestFunction" function eventc.OnServerInvoke(player, labelx) labelx.Text = "Whatever" end

Yet it says labelx is a nil value.

EDIT: Apparently GUIs in StarterGui are not replicating to the server... I just sticked to editing text locally.