title: Excel Source validation error not firing Data Flow task fail event
body: <p>I have a package with a Data Flow task containing Excel Source. DelayValidation is set to True for the Data Flow.</p>
  
  <p>There is an event handler OnTaskFailed at package level. However if the Excel Source validaton fails the OnTaskFailed handler does not execute. It seems the validation error does not fire Task Failed event.</p>
  
  <p>Is it possible to configure it to fire the Task Failed event?</p>