Using predefined OOP in simulink "Matlab function" block

Does anybody know how to implement objects and associated functions (defined by myself in a package) in a simulink "Matlab function" block? I have some problems implementing this piece of code for example:

*function y = fcn(speed,torque)
%#codegen
% mtr = motor.motors.ZR500();
% y = mtr.efficiency(torque*units.Nm,speed*units.rpm,'star');

coder.extrinsic('efficiency','inductionmotor');

mtr = motor.motors.ZR500();
y= mat2str(mtr.efficiency(torque,speed,'star'));

%end*

Errors that I receive from simulink:

*Message - Source - Reported by - Summary*
1) Coder Error - c:/matlab/packages/+motor/inductionmotor.m - Matlab Function - This kind of expression is not supported
2) Coder Error - Matlab function - Matlab function - Parsing failed
3) Block Error - torque - Simulink - Error in port widths or dimensions. Output port 1 is a one dimensional vector with 1 elements.

The reason I use "coder.extrinsic('efficiency','inductionmotor');" is already because I was reading that some function can better be solved in Matlab and simulink will ignore them.

Any help would be highly appreciated! Thanks in advance

[Vikram]

Can you try without using the extrinsic call to the class.

coder.extrinsic isn't supported for declaring MATLAB Classes as extrinsic as per http://www.mathworks.com/help/fixedpoint/ug/how-working-with-matlab-classes-is-different-for-code-generation.html.

Also which version of MATLAB are you working with?