MVC 3 Razor Entity Framwork Error When Saving Update Entity Framework

HI
I am new to MVC, I am currently using MVC3 with Entity Framwork.
I am trying to Edit a record in my DB,but cannot due to an error that i cannot for the life of me fix.
Below is erro That is beeing thrown when excuting this lone of code

db.Tickets.Attach(ticket);

Any assistance will be much appreciated. Thank you :)

An object with the same key already exists in the ObjectStateManager. The ObjectStateManager cannot track multiple objects with the same key.

[HttpPost]
        public ActionResult Edit(Ticket ticket)
        {
            if (ModelState.IsValid)
            {

                Ticket ticket1 = db.Tickets.Single(t => t.TicketID == ticket.TicketID);
                ticket.DateCreated = ticket1.DateCreated;
                db.Tickets.Attach(ticket);
                db.ObjectStateManager.ChangeObjectState(ticket, EntityState.Modified);
                db.SaveChanges();
                return RedirectToAction("Index");
            }
            //ViewBag.CategoryType_CategoryTypeID = new SelectList(db.CategoryTypes, "CategoryTypeID", "CategoryTypeDesc", ticket.CategoryType_CategoryTypeID);
            ViewBag.HighLevelCategory_HighLevelCategoryID = new SelectList(db.HighLevelCategories, "HighLevelCategoryID", "HighLevelCategoryDesc", ticket.HighLevelCategory_HighLevelCategoryID);
            ViewBag.Priority_PriorityID = new SelectList(db.Priorities, "PriorityID", "PriorityDesc", ticket.Priority_PriorityID);
            ViewBag.ServiceProvider_ServiceProviderID = new SelectList(db.ServiceProviders, "ServiceProviderID", "ServiceProviderName", ticket.ServiceProvider_ServiceProviderID);
            ViewBag.Site_SiteID = new SelectList(db.Sites, "SiteID", "SiteName", ticket.Site_SiteID);
            ViewBag.SubCategory_SubCategoryID = new SelectList(db.SubCategories, "SubCategoryID", "SubCategoryDesc", ticket.SubCategory_SubCategoryID);
            ViewBag.Status_TicketStatusID = new SelectList(db.TicketStatus, "TicketStatusID", "TicketStatusDesc", ticket.Status_TicketStatusID);
            return View(ticket);
        }

Tags: C#, Razor, MVC3