GuestBook Using XML Database in ASP.Net

hi freind , i have tried this in c# ,but it is adding only one record to the xml file,not able to append another one ,here is my code... public partial class userdetails2 : System.Web.UI.Page { DataSet ds = new DataSet(); DataTable dt = new DataTable(); string strFilePath = "c:\\guest.xml"; protected void Page_Load(object sender, EventArgs e) { initialisexmlfile(); } public void initialisexmlfile() { dt = ds.Tables.Add("myguest"); DataColumn dc = new DataColumn(); DataColumn[] arr = new DataColumn[1]; dc = dt.Columns.Add("id", typeof(System.Int32)); dc.AutoIncrement = true; dc.AutoIncrementSeed = 1; dc.AutoIncrementStep = 1; arr[0] = dc; dt.PrimaryKey = arr; dt.Columns.Add("datetime",typeof(System.DateTime)); dt.Columns.Add("name", typeof(System.String)); dt.Columns.Add("email", typeof(System.String)); dt.Columns.Add("comments", typeof(System.String)); ds.WriteXml(strFilePath, XmlWriteMode.WriteSchema); // ds.WriteXml("guestbook.xml", XmlWriteMode.WriteSchema); } public void displaydata() { DataView dw = ds.Tables[0].DefaultView; Repeater1.DataSource = dw; Repeater1.DataBind(); } public void populatedataset() { ds.ReadXml(strFilePath, XmlReadMode.IgnoreSchema); } protected void btnSubmit_Click(object sender, EventArgs e) { populatedataset(); DataRow row = ds.Tables[0].NewRow(); row["datetime"] = DateTime.Now ; row["name"] = txtEmail.Text.ToString(); row["email"] = txtName.Text.ToString(); row["comments"] = txtComments.Text.ToString(); ds.Tables[0].Rows.Add(row); DataRow row1 = ds.Tables[0].NewRow(); ds.WriteXml(strFilePath, XmlWriteMode.IgnoreSchema); displaydata(); } } thanks...