Can not load value of parameter into steadyfile

If you use parameters named like internal Matlab functions (e.g. mu) they must be known to Matlab functions. Either rename them or add a dummy statement like mu=0 before

%% Here I load the values of the deep parameters in a loop.
NumberOfParameters = M_.param_nbr;                            % Number of deep parameters.
for i = 1:NumberOfParameters                                  % Loop...
  paramname = deblank(M_.param_names(i,:));                   %    Get the name of parameter i. 
  eval([ paramname ' = M_.params(' int2str(i) ');']);         %    Get the value of parameter i.
end   

That will announce to Matlab that mu is a variable before actually setting it.