Export to Excel error

Dear Friends

when i tried to write coding in a report to export to excel i encounter this automation error as attached with this. I am using Version 4.0, the error coming from
table 370
function Createsheet() this line.

XlWrkSht.Range(GetExcelReference(5) + ':' + xlColID + xlRowID).Columns.AutoFit;



In the Report when i call this function

ExcelBuf.CreateBook;
ExcelBuf.CreateSheet('Book 1','Book 2',COMPANYNAME,USERID); //Error comes here
ExcelBuf.GiveUserControl;
ExcelBuf.ChangePageSetup(2);
ERROR('');