Hello, I have AC # program that gives Excel 20077 series, as its formula is as follows Excel.Worksheet ws_res = (Excel.Worksheet) wb.Worksheets.Add (wrong, wrong, wrong, wrong); Excel.Range range_res = (Excel.Range) ws_res.get_Range ("A1", "HM232"); Range_res.FormulaArray = "= (If ((Sheet 4! A1: Hm 232 = 1.0," + "If (Sheet 4! A1: Hm 232 = 0,1, Sheet 4! A1: Hm 232))) = 1,0, "+" if (((Sheet 4! A1: Hm 232 = 1.0, "+" If (Sheet 4! A1: Hm 232 = 0,1, Sheet 4 ! A1: HM232))) = 0,1, ("+" if (sheet 4! A1: Hm 232 = 1.0, "+" if (sheet 4! A1: HM23 = 0,1 , Sheet 4! A1: HM 232))))); It tells me the exception that the formula is wrong ... but if open Excel 2007 and in a new sheet ( Let's say sheet 5) Select Category A1: HM232 and paste the above formulas directly into the formula bar , And then press Ctrl + Shift + Enter it's all right, ... plz can you tell me how to do this with C #? I know if I have the for...