Reading multiple images from subfolders using MATLAB? (fList = subDir(cDir,'*.jpg'); please help me to figure out the error thank you

%%Copyright (c) 2014 CoVar Applied Technologies
prtPath('beta')
baseDir = fullfile(prtRoot,'dataGen','dataStorage','msrcorid');
if ~exist(baseDir,'dir')
    error('prt:MissingData','Could not locate the MSRCORID database in the folder %s; please download the database and extract it from here: http://research.microsoft.com/en-us/downloads/b94de342-60dc-45d0-830b-9f6eff91b301/default.aspx',baseDir);
end

if nargin < 1
    classList = {fullfile('flowers','single'),'chimneys'};
end
if ~isa(classList,'cell')
    classList = {classList};
end

allClasses = {'aeroplanes\general','aeroplanes\single','animals\cows\general','animals\cows\single','animals\sheep\general','animals\sheep\single',...
    'benches_and_chairs','bicycles\general','bicycles\side view, single','birds\general','birds\single','buildings','cars\front view','cars\general','cars\rear view','cars\side view',...
    'chimneys','clouds','doors','flowers\general','flowers\single','kitchen_utensils\forks','kitchen_utensils\knives','kitchen_utensils\spoons','leaves','miscellaneous',...
    'scenes\countryside','scenes\office','scenes\urban','signs','trees\general','trees\single','windows'};

allClasses = strrep(allClasses,'\',filesep);

if strcmpi(classList{1},'all')
    classList = allClasses;
end

if nargin < 2
    maxNumExamplesPerClass = inf;
end
resizeFact = .5;
imgCell = cell(length(classList),1);
for i = 1:length(classList)
    cDir = fullfile(baseDir,classList{i});
    if ~exist(cDir,'dir')
        error('prt:MissingData','Could not locate the MSRCORID sub-folder %s',cDir);
    end

    fList = subDir(cDir,'*.jpg');%%the error is here it can not locate the sub-folder

      imgCell{i} = cell(min([maxNumExamplesPerClass,length(fList)]),1);
      for imgInd = 1:min([maxNumExamplesPerClass,length(fList)]);
          img = imread(fList{imgInd});
          img = imresize(img,resizeFact);
          imgCell{i}{imgInd,1} = img;
      end
  end

x = cat(1,imgCell{:});
y = prtUtilY(cellfun(@(c)length(c),imgCell));
ds = prtDataSetCellArray(x,y);
ds.classNames = classList;

[Walter Roberson]

subDir is not a Mathworks routine. We would need to see the code for it.