How to clear the contents of an app designer text area?

Below is my code:

% --- create a file to store the QC comments ---
File1 = ['comments/QCcomments_' app.FileName.Value '.txt'];
fid = fopen(File1, 'at'); % append
   fprintf(fid, '%s\n', ['Station No: ' num2str(app.StationNo.Value)]);
   fprintf(fid, '%s\n', char(app.QCcomments.Value));
   fprintf(fid, '%s\n', '');
fclose(fid);

What I want to do is to clear the app.QCcomments contents. I tried to use:

app.QCcomments.Value = '' 

and it did not work.

Many thanks in advance!

[Kojiro Saito]

Is QCcomments defined in properties in App Designer Code view?

properties (Access = public)
    UIFigure         matlab.ui.Figure
    QCcomments       matlab.ui.control.TextArea
 end

[Leon]

Thank you for the reply!

Yes, it is defined like this:

properties (Access = public)
 mainWindow              matlab.ui.Figure
 QCcomments              matlab.ui.control.TextArea
end 

[Kojiro Saito]

So,

app.QCcomments.Value = '';

should clear the text area. Is there any error message?

[Leon]

Working now.

For some reason, it did not work last time I tried it. Sorry about that.