Format Exception

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Data.OleDb;

namespace WindowsFormsApplication1.Forms
{
    public partial class Location_Entry_Frm : Form
    {
        private System.Data.DataTable Locations;

        OleDbConnection MyConnection = new OleDbConnection(@"Provider=Microsoft.Jet.OLEDB.4.0;Data Source=D:\\summary.mdb");
        DataSet ds1;
        OleDbDataAdapter da;

        int id = -1;

        public Location_Entry_Frm()
        {
            InitializeComponent();
        }

        private void Location_Entry_Frm_Load(object sender, EventArgs e)
        {           
            // TODO: This line of code loads data into the 'summaryDataSet.Locations' table. You can move, or remove it, as needed.
            //this.locationsTableAdapter.Fill(this.summaryDataSet.Locations);
        }

        private void btn_View_Click(object sender, EventArgs e)
        {
            BindData();
        }

        private void BindData()
        {           
            MyConnection.Open();
            da = new OleDbDataAdapter("SELECT * FROM Locations",MyConnection);
            ds1 = new DataSet();
            da.Fill(ds1,"Locations");
            dgv_Locations.DataSource = ds1.Tables[0];
            MyConnection.Close();
            id = 1;           
        }

        private void btn_Delete_Click(object sender, EventArgs e)
        {
            rowDelete();
        }

        private void rowDelete()
        {  
            if (id == 1)
            {
                MyConnection.Open();
                OleDbCommand cmd = new OleDbCommand("DELETE from Locations where Sr_Num=" + id, MyConnection);
                cmd.ExecuteNonQuery();
                MyConnection.Close();
                BindData();
            }
            else
            {
                MessageBox.Show("You haven't selected any row");
            }
        }

        private void btn_Close_Click(object sender, EventArgs e)
        {
            this.Close();
        }
    }
}

 private void btn_View_Click(object sender, EventArgs e)
        {
            OleDbConnection MyConnection = new OleDbConnection(@"Provider=Microsoft.Jet.OLEDB.4.0;Data Source=D:\\summary.mdb");
           
            //conn = new OleDbConnection(MyConnection);

            String str2 = "SELECT Locations FROM Locations";

            //Sr_Num,

            OleDbDataAdapter da = new OleDbDataAdapter(str2, MyConnection);

            MyConnection.Open();

            DataSet ds1 = new DataSet();

            OleDbCommandBuilder commandBuilder = new OleDbCommandBuilder(da);

            da.Fill(ds1, "others");

            BindingSource bsource = new BindingSource();

            bsource.DataSource = ds1.Tables["others"];

            dgv_Locations.DataSource = bsource;

            MyConnection.Close();

        }