SQL, VB.NET och C# i en röra...

Jag har en DLL gjord i VB.NET där jag har dessa 2 funktionerna:

    Public Function CreateMail(ByVal dt As DataTable) As String Implements Interfaces.IContact.ICreateMail
        Dim SQL
        Dim myDataReader As OleDbDataReader
        Dim myOleDbCommand As OleDbCommand

        Try
            SQL = "SELECT ID,OrderRubrik,Ordermail,KreditRubrik,Kreditmail,FakturaRubrik,Fakturamail,PasswordRubrik,Passwordmail FROM Mallar WHERE ID=1"
            Dim da As OleDbDataAdapter = New OleDbDataAdapter(SQL.ToString(), Me.myOleDbConnection)

            Dim cmdb As New OleDb.OleDbCommandBuilder(da)
            da.UpdateCommand = cmdb.GetUpdateCommand
            ' da.InsertCommand = cmdb.GetInsertCommand
            ' da.DeleteCommand = cmdb.GetDeleteCommand
            da.Update(dt)

            Me.myOleDbConnection.Close()
            Return "OK"
        Catch ex As Exception
            Return ex.ToString()
        End Try

    End Function

    Public Function GetMail() As DataTable Implements Interfaces.IContact.IGetMail
        Dim SQL
        Dim myDataReader As OleDbDataReader
        Dim myOleDbCommand As OleDbCommand
        Dim mdt As DataTable = New DataTable
        mdt.Clear()

        Try
            SQL = "SELECT ID,OrderRubrik,Ordermail,KreditRubrik,Kreditmail,FakturaRubrik,Fakturamail,PasswordRubrik,Passwordmail FROM Mallar WHERE ID=1"
            Me.myOleDbConnection.Open()
            Dim da As OleDbDataAdapter = New OleDbDataAdapter(SQL.ToString(), Me.myOleDbConnection)

            Dim cmdb As New OleDb.OleDbCommandBuilder(da)
            da.Fill(mdt)

            Me.myOleDbConnection.Close()
            Return mdt
        Catch ex As Exception
            Return mdt
        End Try

    End Function

Sen har jag i ett program gjort i C# den här koden:

		private void btnSave_Click(object sender, System.EventArgs e)
		{
			IContact cc;
			cc=(IContact)Activator.GetObject(typeof(IContact),ConfigurationSettings.AppSettings["Contact"].ToString());
			DataTable dt = new DataTable();
			dt.Columns.Add("ID", typeof(int));
			dt.Columns.Add("OrderRubrik", typeof(string));
			dt.Columns.Add("Ordermail", typeof(string));
			dt.Columns.Add("KreditRubrik", typeof(string));
			dt.Columns.Add("Kreditmail", typeof(string));
			dt.Columns.Add("FakturaRubrik", typeof(string));
			dt.Columns.Add("Fakturamail", typeof(string));
			dt.Columns.Add("PasswordRubrik", typeof(string));
			dt.Columns.Add("Passwordmail", typeof(string));

            DataRow dr = dt.NewRow();
			dr["ID"] = 1;
			dr["OrderRubrik"] = txtOrderRubrik.Text;
			dr["Ordermail"] = txtOrderText.Text;
			dr["KreditRubrik"] = txtKreditRubrik.Text;
			dr["Kreditmail"] = txtKreditText.Text;
			dr["FakturaRubrik"] = txtFakturaRubrik.Text;
			dr["Fakturamail"] = txtFakturaText.Text;
			dr["PasswordRubrik"] = txtPasswordRubrik.Text;
			dr["Passwordmail"] = txtPasswordText.Text;
			dt.Rows.Add(dr);

			txtFakturaText.Text =cc.ICreateMail(dt);
		}

		private void Epostmallar_Load(object sender, System.EventArgs e)
		{
			IContact cc;
			cc=(IContact)Activator.GetObject(typeof(IContact),ConfigurationSettings.AppSettings["Contact"].ToString());
			DataTable dt = new DataTable();
			dt = cc.IGetMail();
			foreach(DataRow dr in dt.Rows)
			{
				txtFakturaRubrik.Text = dr["FakturaRubrik"].ToString();
				txtFakturaText.Text = dr["Fakturamail"].ToString();
				txtOrderRubrik.Text = dr["OrderRubrik"].ToString();
				txtOrderText.Text = dr["Ordermail"].ToString();
				txtKreditRubrik.Text = dr["KreditRubrik"].ToString();
				txtKreditText.Text = dr["Kreditmail"].ToString();
				txtPasswordRubrik.Text = dr["PasswordRubrik"].ToString();
				txtPasswordText.Text = dr["Passwordmail"].ToString();
			}
		}

Det funkar fint att hämta infon men när jag sen ska uppdatera sparas en ny post i databasen istället för att uppdatera.
Kan inte förstå varför, någon som har ett tips?