Problem while generating Excel file from classic report

Hi everyone,
I am trying to generate an Excel file from a report.I have a trouble with the following line of code:

ExcelBuf.AddColumn('(01)',FALSE,'',TRUE,FALSE,TRUE,'');

I want the value (01) to be displayed in the column header, but what I get in the Excel file is -1.
How can I display what I want?
Thanks in advance :)