how to simplify a symmatrix expression

Three symmatrix type variables: Cn, MW0 and MDW0. I apply the command "simplify(Cn*(MW0+ MDW0) - Cn*MW0)" and I hope it output " Cn * MDW0". However, I only got an error "Incorrect number or types of inputs or outputs for function 'simplify' ". How to solve this issue? The following code block could reproduce this error. Thanks a lot.

syms MW0  [3 3] matrix 
syms MDW0 [3 3] matrix 
syms Cn [3 3] matrix 
detlaC_1 = BiasCdiff1 - Cdiff1
sipReC_1 = simplify(BiasCdiff1 - Cdiff1)  % the line throw out error

Answer 1

[Walter Roberson]

syms MW0  [3 3] matrix 
syms MDW0 [3 3] matrix 
syms Cn [3 3] matrix
expression = Cn*(MW0+ MDW0) - Cn*MW0

expression = 

class(expression)

ans = 'symmatrix'

So the expression returns a symmatrix not a sym and not a symfun

methods(expression)

Methods for class symmatrix:

adjoint        csc            display        horzcat        kron           log            mtimes         power          sin            symmatrix2sym  uminus         
cat            ctranspose     double         inv            latex          minus          ne             pretty         size           tan            uplus          
conj           det            eq             isempty        ldivide        mldivide       norm           rdivide        subs           times          vertcat        
cos            diff           exp            isequal        length         mpower         numel          rhs            sym            trace          vpa            
cot            disp           gradient       isequaln       lhs            mrdivide       plus           sec            symmatrix      transpose      

Static methods:

empty          

Notice that simplify() is not one of the listed methods. Which is to say, that simplify() is not defined for expressions involving symmatrix.