Datagrid edit button is not working properly

SqlConnection conn = new SqlConnection(System.Web.Configuration.WebConfigurationManager.AppSettings["ConnectionString"]);
    SqlDataAdapter da =new SqlDataAdapter();
    DataSet ds = new DataSet();
    SqlCommand cmd = new SqlCommand();
        protected void Page_Load(object sender, EventArgs e)
    {
        try
        {
        if (!IsPostBack)
        {
            populatedata();
            //BindData();
        }
    }
    catch (Exception ex)
    {
    }
                                                
    }

    public void populatedata()
    {
        try
        {
            if (conn.State == ConnectionState.Closed)
            {
                conn.Open();
            }
            cmd.CommandText = "select O.Order_ID,O.Package_ID,O.No_Of_Images,SC.Package_Name,SC.Package_ID,O.Remarks,O.Original_Quote_Amount,O.Revised_Quote_Amount,O.Amount_Received,(O.Revised_Quote_Amount-O.Amount_Received) As Balance_Amount,O.Status_Code from tbl_mst_Order O,tbl_mst_Service_Catalogue SC where O.Package_ID=SC.Package_ID";
            cmd.Connection = conn;
            da = new SqlDataAdapter(cmd);
            da.Fill(ds, "tbl_mst_Order");
            cmd.ExecuteNonQuery();
            //Gdordermgmt.DataSource = ds;
           // Gdordermgmt.DataBind();
            cmd.CommandText = "Select Status_Id, Status_Code,Status_Description from tbl_mst_Order_Status where Is_Status_Active=1";
            cmd.Connection = conn;
            da = new SqlDataAdapter(cmd);
            da.Fill(ds, "tbl_mst_Order_Status");
            cmd.ExecuteNonQuery();
            BindData();
        }
        catch (Exception ex)
        {
        }
            finally
            {
                conn.Close();
            }
    }
    protected void BindData()
    {
        Gdordermgmt.DataSource = ds.Tables["tbl_mst_Order"];
        Gdordermgmt.DataBind();
    }
    protected void Gdordermgmt_PageIndexChanged(object sender, DataGridPageChangedEventArgs e)
    {
        try
        {
            Gdordermgmt.CurrentPageIndex = e.NewPageIndex;
            populatedata();
            //BindData();
        }
        catch(Exception ex)
        {
        }
       // Gdordermgmt.DataSource = ds;
        //Gdordermgmt.DataBind();
      // BindData();
    }
    public void Gdordermgmt_editcmd(object sender, DataGridCommandEventArgs e)
    {          
      
      Gdordermgmt.EditItemIndex = e.Item.ItemIndex;
      populatedata();
      //BindData();
       //ResetPageIndex(Gdordermgmt,View);
      //BindData();
    
    }
   
    protected void Gdordermgmt_cancelcmd(object sender, DataGridCommandEventArgs e)
    {
        Gdordermgmt.EditItemIndex = -1;
        populatedata();
        //BindData();
      
      //  Gdordermgmt.DataSource = ds;
       // Gdordermgmt.DataBind();
       // BindData();
    }
        protected void Gdordermgmt_updatecmd(object sender, DataGridCommandEventArgs e)
      {
          TextBox txtamtrecieved = (TextBox)e.Item.FindControl("txtamtrecieved");
          TextBox txtrevisedqtamt = (TextBox)e.Item.FindControl("txtrevisedqtamt");
          TextBox tx = new TextBox();
          tx = (TextBox)e.Item.Cells[8].Controls[0];
          //cmd.CommandType = CommandType.Text;
          cmd.CommandText = "Update tbl_mst_Order" +
                           " Set Revised_Quote_Amount= '" + txtrevisedqtamt.Text + "', Received_Amount='" + txtamtrecieved.Text + "'where Order_ID='" + e.Item.ItemIndex + "'";
          cmd.Parameters.Add(new SqlParameter("@txtrevisedqtamt", SqlDbType.Text));
          cmd.Parameters["@txtrevisedqtamt"].Value = tx.Text;
          cmd.ExecuteNonQuery();
          ds.AcceptChanges();
          Gdordermgmt.EditItemIndex = -1;
          Gdordermgmt.DataBind();
          //da.Update(ds);
   
       }
    protected void Gdordermgmt_Bounddata(object sender, DataGridItemEventArgs e)
    {
        if (e.Item.ItemType == ListItemType.Item || e.Item.ItemType == ListItemType.AlternatingItem)
        {
            DropDownList list = (DropDownList)e.Item.FindControl("ddlorderstatus");
            if (list != null)
            {
                list.DataSource = ds.Tables["tbl_mst_Order_Status"];
                list.DataValueField = ds.Tables["tbl_mst_Order_Status"].Columns[0].ToString();
                list.DataTextField= ds.Tables["tbl_mst_Order_Status"].Columns[1].ToString();
                list.DataBind();
            }
        }
        else
        {
        }
    }