Model return false in Unit testing using asp.net mvc

I need help. I have this code in my unit test method.

My testMethod Code:
 FormCollection fakeForm = new FormCollection();
        fakeForm.Add("Id", "241");
        fakeForm.Add("Description", "Unit Test");
        target.ValueProvider = fakeForm.ToValueProvider();
        var result = target.Insert() as ViewResult;

My Controller code:

public ActionResult Insert()
    {
         var newSelection = new Codes();
         var insert = TryUpdateModel(newSelection);
         if(insert)
           {
                //Save Method
           }
         else
           {
                //no Update
           }
    }

How do I need set insert true to pass my test case?

Thanks in advance.