shame:
1. an unlucky situation:
~~~It's a shame that the concert had to be cancelled.
~~~"Douglas is having to miss the school concert because he's ill."
"Oh, what a shame!"

2. a bad feeling of guilt


shame on you:
used to tell someone that they should feel sorry for something they did(can be friendly):
~~~Shame on you for being so unkind.
~~~HUMOROUS You mean you were in town and you didn't come and see us - shame on you!