I am trying to create a custom tab in the admin so that my client can add tracking to an order. I have the new tab on an order however I am unable to subscribe to the save event. Anyone got any ideas what I am doing wrong?

public partial class OrderTracking : UCommerce.Presentation.Web.Controls.ViewEnabledControl<IEditOrderView>
    {

        protected void Page_Load(object sender, EventArgs e)
        {
            if (!Page.IsPostBack)
            {
                txtTrackAndTrace.Attributes.Add("style", "width: 500px");
                PurchaseOrder purchaseOrder = PurchaseOrder.SingleOrDefault(x => x.OrderId ==  View.OrderId);
                ICollection<Shipment> shipments = purchaseOrder.Shipments;
                Shipment shipment = purchaseOrder.Shipments.FirstOrDefault();

                txtTrackAndTrace.Text = shipment.TrackAndTrace;

                View.Saved += new EventHandler<EntityCommandEventArgs<PurchaseOrder>>(this.HandleSaveOrderTracking);


            }
        }

        private void HandleSaveOrderTracking(object sender, EventArgs e)
        {
            PurchaseOrder purchaseOrder = PurchaseOrder.SingleOrDefault(x => x.OrderId == View.OrderId);
            ICollection<Shipment> shipments = purchaseOrder.Shipments;
            Shipment shipment = purchaseOrder.Shipments.FirstOrDefault();

            shipment.TrackAndTrace = Server.HtmlEncode(txtTrackAndTrace.Text);

            shipment.Save();
        }


       
    }