c# - error CS0117 in Unity -

i working in unity 5.1 beginner, got error , i've no idea how solve this:

assets/sampleassets/cameras/scripts/freelookcam.cs(39,32): error cs0117: `unityengine.screen' not contain definition `cursor'

my script is:

   private void ondisable()     {         screen.cursor.lockstate = cursor.visible;     }

just remove screen. code becomes:

private void ondisable(){   curser.lockstate = cursorlockmode.locked; }

however, if want hide/display cursor use this:

cursor.visible = true; cursor.visible = false;

Core code