Error in wPDF WPTools demo

  • Using wPDF4 Standard with XE2.
    Using the wPDF demo in the WPTools folder.
    In the code for the "to PDF" button I am adding my license registration
    WPDF_Start('mylicname', 'myliccode');
    Doing nothing else, I click "to PDF" button.
    Then a message apears telling "Cannot start PDF Document".
    How can I solve this problem ?

    Tried uncommenting pdf.DebugMode line, but there is no information in the manual about what it does.