undefined function for input arguments of type cell

Im trying to produce a regime swithing table using matlab. everything works fine, until the last step. "Undefined function 'MS_Regress_Fit_tvtp' for input arguments of type 'cell'" comes in red, and i cant proceed.

could someone tell me where goes wrong?

here is the code.

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addpath('m_Files_tvtp_20121113'); % add 'm_Files' folder to the search path
addpath('data_Files');

logRet=importdata('tryout.mat');  % load some Data.

dep=logRet(:,1:2:3);                  % Defining dependent variable from .mat file
constVec=ones(length(dep),1);       % Defining a constant vector in mean equation (just an example of how to do it)
indep{1}=constVec;                  % Defining some explanatory variables
%indep{2}=constVec;                  % Defining some explanatory variables
% indep{3}=constVec;                  % Defining some explanatory variables
px=[constVec logRet(:,4)];
px=constVec;

k=2;                                % Number of States
S{1}=[1 1 1];                        % Defining which parts of the equation will switch states (column 1 and variance only)
S{2}=[1 1 1];                        % Defining which parts of the equation will switch states (column 1 and variance only)
% S{3}=[1 1];                        % Defining which parts of the equation will switch states (column 1 and variance only)

advOpt.distrib='Normal';            % The Distribution assumption ('Normal', 't' or 'GED')
advOpt.distrib='t';                 % The Distribution assumption ('Normal', 't' or 'GED')
advOpt.std_method=2;                % Defining the method for calculation of standard errors. See pdf file for more details
advOpt.diagCovMat=1;

[Spec_Out]=MS_Regress_Fit_tvtp(dep,indep,px,k,S,advOpt); % Estimating the model

[James Tursa]

Is MS_Regress_Fit_tvtp on the path? What do you get when you type:

which MS_Regress_Fit_tvtp