Im facing problem when trying to apply data annotation. In my case im passing FormCollection in controller

[HttpPost]         
public ActionResult Create(string Button, FormCollection collection)
{
if (ModelState.IsValid)
      {
      }
else
      {
      }
}

and in ModelState.IsValid condition always have true value. Although i have left some blank fields in View. Also EnableClientValidation() is also applied in View for client side validation but its not working. what may be the problem