create Excel from csv; error in subtotalhreiben von Software

Hi, since three years the function worked without problems. This function opens a CSV file, sort 4 columns, inserts the subtotals, formatted the tables and stores the results in an Excel file. Now I had to recompile the program and get 2 error: "Microsoft Excel could not determine which row contains the column labels that are necessary for this command." "The subtotal method of range properties could not be executed." The source code I have not changed, only the NET version (3.5 to 4.0) Who can help in the short term? In the attachment you find the csv source, the function and the excel (destination, created manually) Regards Jürgen