It's good practice. Naturally, you will find I am right. But I'm used to that.
Here's a ballot access story from the last election. It states quite clearly that had Nader not qualified himself as a write-in candidate per Georgia law votes for him would not have counted. See? And he was denied access in other states. Hence, you could vote for him, but the votes would not count. Just like I said.
http://www.tallahassee.com/mld/talla...al/9782922.htm