New to Java

I need a little help,

I'm using Jbuilder to write a java program.
I have wrote a class file which is my superclass and i have created another file. I want the second file to be the subclass and inherit from the superclass.

I have used the extends function, however it compiles through command prompt but when i try to make the file in Jbuilder it says that it cannot resolve the symbol.

Any suggestions