how to display gridview selected row in label in asp.net c#

protected void OnSelectedIndexChanged(object sender, EventArgs e)
{
    string name = GridView1.SelectedRow.Cells[0].Text;
    string country = (GridView1.SelectedRow.FindControl("lblCountry") as Label).Text;

    lblValues.Text = "<b>Name:</b> " + name + " <b>Country:</b> " + country;
}

I am using this method

Label19.Text = GridView1.SelectedRow.Cells[1].Text;
Session("pass_id") = Label19.Text
Response.Redirect("admin_detaileddashboard.aspx")

Refer

gridview.selectedrow[^]

protected void GridView1_SelectedIndexChanging(object sender, GridViewSelectEventArgs e)
{
GridView1.Rows[e.NewSelectedIndex].BackColor = System.Drawing.Color.Black;
string str = GridView1.Rows[e.NewSelectedIndex].Cells[5].Text;
Label8.Text = str.ToString();
}

when i try this code it shows label is empty or null