title: attempt to index global 'message' (a nil value) Lua Message script
body: <p>Currently, I'm working on a simple Lua Roblox script that is supposed to turn the parent part blue when "/blue" is entered in the chat by ANY player. When run, it returns the error "attempt to index global 'message' (a nil value)" in the output. Also, when I hover my cursor over "message" it says "unknown global 'message'". I am sure I'm doing something terribly wrong as I am new to the language. I have tried moving the script into Workspace and Chat (of course changing local part when I do) but those don't help. I'm confident it's a code issue specifically defining a global variable.</p>
  
  <pre><code>local part = script.Parent
  
  local function scan()
      if message:sub(1,5) == "/blue" then
          part.BrickColor = BrickColor.Blue()
      end
  end
  
  scan()
  </code></pre>