Gridview row deleting Error?

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Data.SqlClient;
using System.Data;
using System.IO;


public partial class ProductImages : System.Web.UI.Page
{
SqlConnection con = new SqlConnection(@"Data Source=.\SQLEXPRESS;AttachDbFilename=D:\SVN\Ecommerce\App_Data\ECommerce.mdf;Integrated Security=True;User Instance=True");
//dbOperations objDO = new dbOperations();
DataTable dt = new DataTable();
//dbconnection objcon = new dbconnection();
//string strValue = string.Empty, status = string.Empty, strField = string.Empty;
//bool result;

SqlCommand objcmd = new SqlCommand();
//SqlDataAdapter objda = new SqlDataAdapter();

protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
bind();
fillProduct();
}
public void conn()
{
if (con.State == ConnectionState.Open) con.Close();
con.Open();
objcmd.Connection = con;
}

protected void Save(object sender, EventArgs e)
{

conn();
string ImgSmall = Path.GetFileName(fileuploadimgsmall.PostedFile.FileName);
fileuploadimgsmall.SaveAs(Server.MapPath("ImagesSmall/" + ImgSmall));

string ImgLarge = Path.GetFileName(fileuploadimglarge.PostedFile.FileName);
fileuploadimglarge.SaveAs(Server.MapPath("ImagesLarge/" + ImgLarge));

objcmd = new SqlCommand("Insert into TBL_PDT_IMG(PDT_ID,IMG_NAME,IMG_DESC,PDT_IMAGE_SMALL,PDT_IMAGE_LARGE,IS_PRIMARY) values(@PDT_ID,@IMG_NAME,@IMG_DESC,@PDT_IMAGE_SMALL,@PDT_IMAGE_LARGE,@IS_PRIMARY)",con);
fillProduct();
objcmd.Parameters.AddWithValue("@PDT_ID", ddlproduct.SelectedValue);
objcmd.Parameters.AddWithValue("@IMG_NAME", txtimgname.Text.Trim());
objcmd.Parameters.AddWithValue("@IMG_DESC", txtimgdesc.Text.Trim());
objcmd.Parameters.AddWithValue("@PDT_IMAGE_SMALL", "ImagesSmall/" + ImgSmall);
objcmd.Parameters.AddWithValue("@PDT_IMAGE_LARGE", "ImagesLarge/" + ImgLarge);
objcmd.Parameters.AddWithValue("@IS_PRIMARY", chkstatus.Checked);
objcmd.ExecuteNonQuery();

bind();


}


public void fillProduct()
{
//conn();
try
{
SqlCommand cmd = new SqlCommand("select PDT_ID,PDT_NAME from TBL_PDT",con);
SqlDataAdapter da = new SqlDataAdapter(cmd);
DataTable dt = new DataTable();
da.Fill(dt);
ddlproduct.DataSource = dt;
ddlproduct.DataTextField = "PDT_NAME";
ddlproduct.DataValueField = "PDT_ID";
ddlproduct.DataBind();
// return dt;
}
catch (Exception ex)
{
}

}



public void bind()
{
conn();
//fillProduct();
//con.Open();
//// objcon.con.Open();
objcmd = new SqlCommand("select * from TBL_PDT_IMG LEFT OUTER JOIN TBL_PDT ON TBL_PDT_IMG.PDT_ID=TBL_PDT.PDT_ID", con);
SqlDataAdapter da = new SqlDataAdapter(objcmd);
DataSet ds = new DataSet();
da.Fill(ds);
//con.Close();
if (ds.Tables[0].Rows.Count > 0)
{
GridView1.DataSource = ds;
GridView1.DataBind();
}
// GridView1.DataSource = objcmd.ExecuteReader();
// GridView1.DataBind();
////objcon.con.Close();
// con.Close();
}
protected void GridView1_RowCommand(object sender, GridViewCommandEventArgs e)
{
try
{
if (e.CommandName == "Select")
{
// Img();

int index = Convert.ToInt32(e.CommandArgument);
GridViewRow row = GridView1.Rows[index];
lblpdtid.Text = GridView1.Rows[index].Cells[0].Text;
ddlproduct.SelectedItem.Text = GridView1.Rows[index].Cells[1].Text;
txtim