Matlab engine for java: Calling functions from class objects

I'm currently trying to fiddle with the Matlab engine for Java. So far I'm able to call Matlab functions and self-written functions (with engine.feval(0, "matlabFunction"). But as soon as I try to call a function from a class object (with "engine.feval(0, "matlabClass.classFunction);") I get an error "Unknown function or variable". In Matlab, the class function works fine and I can call the very same function with "engine.eval("matlabClass.classFunction");" without problems, so I assume the problem is not on the Matlab side.

Is it possible at all to call a function from within a matlab class object with the matlab engine? If yes, can someone give me a hint on how to do that?