Sorry, this lecture so hard to me. I can google and understand a little knowledge. But it’s still too difficult for me. By the way, anyone can explain to me what’s the matter with my program?
I did everything follow the guide in the lecture,
but there is something wrong here. 
Does MonoBehaviour have the same colour as your classname? If not, there might be a problem with Visual Studio. Please watch lecture “Fixing Visual Studio Problems” (currently #4).
NullReferenceException means that a reference (“link”) to an instance is missing. Double click on the error message to see to which line in your code it is referring. If you exposed a field in the Inspector, make sure that it’s not empty.
Did this fix it?
See also:
