New Post: .xlsx. Date cell import to DataTable

Hi!
I'm tried to convert .xlsx file to DataTable format by using NPOI 2.0 library. It's OK, but I have a problem with convert to string date cell. When I try to use construction like row.GetCell(j).ToString() - it's threw exception "Cannot get numeric value from a text cell". I tried to use DateCellValue property, but it also threw this exception. With other cell formats it's work good.
Function, that I use it's:

private DataTable xlsxToDT(string fileName)
        {
            DataTable table = new DataTable();
            XSSFWorkbook workbook = new XSSFWorkbook(new FileStream(fileName, FileMode.Open, FileAccess.Read));
            ISheet sheet = workbook.GetSheetAt(0);
            IRow headerRow = sheet.GetRow(0);
            int cellCount = headerRow.LastCellNum;
            for (int i = headerRow.FirstCellNum; i < cellCount; i++)
            {
                DataColumn column = new DataColumn(headerRow.GetCell(i).StringCellValue);
                table.Columns.Add(column);
            }
            int rowCount = sheet.LastRowNum;
            for (int i = (sheet.FirstRowNum); i < sheet.LastRowNum; i++)
            {
                IRow row = sheet.GetRow(i);
                DataRow dataRow = table.NewRow();
                for (int j = row.FirstCellNum; j < cellCount; j++)
                {
                    if (row.GetCell(j) != null)
                    {
                        //EXCEPTION GENERATING IN THIS CODE
                        dataRow[j] = row.GetCell(j).ToString();
                        ////////////////////////////
                    }
                }
                table.Rows.Add(dataRow);
            }
            workbook = null;
            sheet = null;
            return table;
        }

Please help me with my problem.

P.S. - sorry for my English :)