Error using y_ExtractROISignal (line 239)

I have 3 groups of subjects, and I am using a ROIList.mat file for all 3 groups. It works without issues for 2 groups. For the third, it gives below error. What does it mean?-
Error using y_ExtractROISignal (line 239)
An UndefinedFunction error was thrown on the workers for 'MaskROILabel'.  This might be because the file
containing 'MaskROILabel' is not accessible on the workers.  Use addAttachedFiles(pool, files) to specify the
required files to be attached.  See the documentation for 'parallel.Pool/addAttachedFiles' for more details.
Error in DPARSFA_run (line 2501)
        parfor i=1:AutoDataProcessParameter.SubjectNum
Error in DPARSFA>pushbuttonRun_Callback (line 1795)
Error in gui_mainfcn (line 95)
Error in DPARSFA (line 30)
    gui_mainfcn(gui_State, varargin{:});
Caused by:
    Undefined function or variable 'MaskROILabel'.


Error while evaluating UIControl Callback.
Thank you.


What's the ROI file?