title: MVC Models not successfully updated but can't find reason
body: <p>This has been driving me nuts.</p>
  
  <p>I keep getting the following exception</p>
  
  <p>System.InvalidOperationException: The model of type 'Models.Expense' was not successfully updated.
     at System.Web.Mvc.Controller.UpdateModel[TModel](TModel model, String prefix, String[] includeProperties, String[] excludeProperties, IDictionary`2 valueProvider)
     at System.Web.Mvc.Controller.UpdateModel[TModel](TModel model)
     atMVC.Controllers.BaseExpenseController.Edit(String id, FormCollection collection) in C:\Projects\Expenses.MVC\Controllers\BaseExpenseController.cs:line 109</p>
  
  <p>But I can't track down why it is not updating, nothing in the exception suggests why it has not updated.</p>
  
  <p>Any pointers?</p>