Entity ’ becomes wrong character

Hello list,

I assume that I found a small bug in the stylesheets. Maybe the bug 
isn't in the stylesheets but in the DTD. I don't know.

If I use the entity ’ within my documents, I get always the wrong 
character. Since I don't know the proper english (and german) name for 
it, I put an example online:

http://www.xshare.com/fehler.html

It would be nice, if someone could have a  look at it.

Regards,

Oliver Fischer