How to resolve the error "Child list for field <TableName> cannot be created. " in C# ?

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C#

XML

DataGridView

Hi, i have DataGridView in a form which is loaded from a XML file when the form is loaded. This XML file is updated every time a new row is added to the datagridview.
Initially it was working fine but now it is showing the following error :
"Child list for field <tablename> cannot be created." where <tablename> is the name of the table.

This is what i am doing :

DataSet dataSet = new DataSet();
dataSet.ReadXml(@"D:\HostAdded.xml");
DataRow row = dataSet.Tables[0].NewRow();
row.ItemArray = new object[] { txthostname.Text, ipAddr, txtusername.Text, txtpassword.Text };
dataSet.Tables[0].Rows.Add(row);
dataGridView1.DataSource = dataSet;
dataGridView1.DefaultCellStyle.ForeColor = Color.Red;
dataGridView1.AutoGenerateColumns = false;
txtLog.AppendText(Environment.NewLine + "\nRow added successfully");
createXML();

createXML()

DataTable dt = new DataTable();
            foreach (DataGridViewColumn col in dataGridView1.Columns)
            {
                dt.Columns.Add(col.HeaderText);
            }
            foreach (DataGridViewRow row in dataGridView1.Rows)
            {
                DataRow dRow = dt.NewRow();
                foreach (DataGridViewCell cell in row.Cells)
                {
                    dRow[cell.ColumnIndex] = cell.Value;
                }
                dt.Rows.Add(dRow);
            }
            DataSet ds = new DataSet();
            ds.Tables.Add(dt);
            ds.WriteXml(@"D:/HostAdded.xml");

Please help!!!
Thanks :)