Java class diagram - extending built-in classes

Hi all,

I'm a new user to PowerDesigner, and I am starting with a basic class diagram. I've created some classes that should extend the built-in class java.lang.Exception. However, when I try to select a class to inherit from, I cannot find Exception; the only classes that are listed are the ones that I have created myself.

Is there something special I must do to be able to use the built-in Java classes? I've read the product manual trying to figure this out, and had no luck. I'd appreciate any help figuring this out.