Getting error into Update query

{

      System.Data.OleDb.OleDbConnection MyConnection;

      System.Data.OleDb.OleDbCommand myCommand = new System.Data.OleDb.OleDbCommand();

      string sql = null;

      MyConnection = new System.Data.OleDb.OleDbConnection("Provider=Microsoft.ACE.OLEDB.12.0;Data Source=d:\\csharp.net-informations.xlsx;Extended       Properties=Excel 12.0 Xml;");

      MyConnection.Open();

      myCommand.Connection = MyConnection;

      sql = (@"Update [Sheet1$] set (candidatefname='" + txtFName.Text + "', candidatemname='" + txtMName.Text + "', candidatelname='" + txtLName.Text + "',       dob='" + dtpDOB.Value + "', sex='" + cmbSex.Text + "', currentaddress='" + txtCurrentAddress.Text + "', permanentaddress='" + txtParmanentAddress.Text +       "', mobilenumber='" + txtMobile.Text + "', mailid='" + txtMailID.Text + "', maritalstatus='" + cmbMaritalStatus.Text + "', experience='" + txtExperience.Text + "',       departmentname='" + cmbDepartment.Text + "') where SrNo='" + cID + "' ");

      myCommand.CommandText = sql;

      myCommand.ExecuteNonQuery();

      MyConnection.Close();

}

catch (Exception ex)

{

      MessageBox.Show(ex.ToString());