Error 'Index was out of range. Must be non-negative and less than the size of the collection' in ASP.Net

 aSPX.CS

 protected void OnRowDeleting(object sender, GridViewDeleteEventArgs e)
    {
        string strConnString = ConfigurationManager.ConnectionStrings["ConnStr"].ConnectionString;
        SqlConnection con = new SqlConnection(strConnString);
        DataTable dt = new DataTable();
        using (SqlConnection conn = new SqlConnection(strConnString))
        {
            int selectedRow = GridView1.SelectedIndex;
            GridViewRow theRow = GridView1.Rows[selectedRow];
            string str = ("Delete TDLoanRate where Id=@id");
            SqlCommand insert = new SqlCommand(str, con);
            insert.Parameters.AddWithValue("@id", Convert.ToInt32(theRow.Cells[0].Text));
            using (SqlDataAdapter sda = new SqlDataAdapter())
            {
                insert.Connection = con;
                con.Open();
                sda.SelectCommand = insert;
                sda.Fill(dt);
                GridView1.DataSource = dt;
                GridView1.DataBind();
            }
            con.Open();
        }
    }

 Aspx.net

<asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="False" OnSelectedIndexChanged="GridView1_SelectedIndexChanged" Width="371px" PageSize="5" AllowSorting="True" onsorting="GridView1_Sorting" OnRowDeleting="OnRowDeleting">
    <Columns>
        <asp:BoundField DataField="Id" HeaderText="id" SortExpression="Id" />
        <asp:BoundField DataField="LoanType" HeaderText="LoanType" SortExpression="LoanType" />
        <asp:BoundField DataField="LoanTerm" HeaderText="Term(Years)" SortExpression="LoanTerm" />
        <asp:BoundField DataField="LoanRate" HeaderText="LoanRate" SortExpression="LoanRate" />
        <asp:BoundField DataField="LoanEffectFrom" HeaderText="Loan Effect From" SortExpression="LoanEffectFrom" />
        <asp:BoundField DataField="LoanMaturity" HeaderText="Loan Maturity Date" SortExpression="LoanMaturity" />
        <asp:CommandField HeaderText="Edit" SelectText="Edit" ShowSelectButton="True" />
        <asp:CommandField HeaderText="Delete" ShowDeleteButton="True" ShowHeader="True" />
    </Columns>
</asp:GridView>

Index was out of range. Must be non-negative and less than the size of the collection in below line.

int selectedRow = GridView1.SelectedIndex;