Creating subclass based on RF Toolbox rfckt package superclass

Hello,

I am trying to inherit an "rfckt.seriesrlc" class inside my own class "Shunt_Series_LC_Resonator" so that I can add some extra properties and still be able to use the other rfckt classes (such as cascade, series, etc)

The Shunt_Series_LC_Resonator Class is defined as follows:

    classdef Shunt_Series_LC_Resonator < rfckt.seriesrlc      
        properties
             myProperty;
        end
        methods
             function obj = Shunt_Series_LC_Resonator(vargin)
                 obj = [e-mail](vargin);
             end
        end
    end

When I call the class using:

A = Shunt_Series_LC_Resonator;

I get the following error:

??? Error using ==> Shunt_Series_LC_Resonator The specified super-class 'rfckt.seriesrlc' contains a parse error or cannot be found on MATLAB's search path, possibly shadowed by another file with the same name.

I checked that the following works:

B = rfckt.seriesrlc;

I looked at the Matlab Path and it contains:

/Applications/MATLAB_R2010a.app/toolbox/rf/rf

The rfckt package is found in this folder and the address of the seriesrlc class is:

/Applications/MATLAB_R2010a.app/toolbox/rf/rf/@rfckt

however it won't let me add this directory to the path.

Does anyone understand why I can't inherit this class? Does it have something to do with the fact that it is under the rfckt package? Are there some kinds of classes that cannot be used as superclasses?

Thank you in advance for your help,

Dylan