为什么IE6导不出来Excel

在IE7、8 FF，都可以，就是在IE6上不行。
我的方法： public void CreateExcel(DataTable dt, string fileName)
        {
            HttpResponse response = HttpContext.Current.Response;
            response.ContentEncoding = Encoding.GetEncoding("GB2312");
            response.AppendHeader("Content-Disposition", "attachment;filename=" + fileName);
            string s = "";
            string str2 = "";
            DataRow[] rowArray = dt.Select();
            int num = 0;
            int count = dt.Columns.Count;
            num = 0;
            while (num < count)
            {
                if (num == (count - 1))
                {
                    s = s + dt.Columns[num].Caption.ToString() + "\n";
                }
                else
                {
                    s = s + dt.Columns[num].Caption.ToString() + "\t";
                }
                num++;
            }
            response.Write(s);
            foreach (DataRow row in rowArray)
            {
                for (num = 0; num < count; num++)
                {
                    if (num == (count - 1))
                    {
                        str2 = str2 + row[num].ToString() + "\n";
                    }
                    else
                    {
                        str2 = str2 + row[num].ToString() + "\t";
                    }
                }
                response.Write(str2);
                str2 = "";
            }
            response.End();
        }