Test Scene with Simple Luup Code

I am testing a scene with Luup code and it is not working correctly. It is a very simple scene too.

When light1 turns off, turn off light2. The Luup code is to allow it to run only during the day (since I am testing at night).

I put this Luup code in but when I turn off light1 it still turns off light2.

return luup.is_night() == false

In my log I do see an error on my scene. I am not sure what this means since I think I only need to return false to not run the scene, correct?
LuaInterface::CallFunction_Scene Scene 9 failed attempt to call a nil value

Any suggestions?