Why wont this script add 1 to the value? red underline

As the title says..

local Player = game.Players.LocalPlayer
local DataStore = game.ServerScriptService.DataStore
local Workspace = game.Workspace
local ReplicatedStorage = game.ReplicatedStorage
local ServerStorage = game.ServerStorage
local StarterPlayer = game.StarterPlayer

game.Players.PlayerAdded:Connect(function(plr)
	if Workspace.StarterItemsUpgraded.StarterMonitorUpgraded.ScreenGui.Active == true then
		wait(math.random(10,25))  
		game.Players.LocalPlayer:WaitForChild("leaderstats").Followers.Value +1
 -- Plus sign is red underline 
		end
	end
end)

Try That

game.Players.PlayerAdded:Connect(function(Player)
 if Workspace.StarterItemsUpgraded.StarterMonitorUpgraded.ScreenGui.Active == true then
 wait(math.random(15,20))
 plr.leaderstats.Followers.Value = plr.leaderstats.Followers.Value + 1
      end
end)