title: error : The field ID must be a number. in @Html.DropDownListFor method
body: <p>My model:</p>
  
  <pre><code>public class ViewRequestModel
  {
      [Required(ErrorMessage = "some")]
      [Display(Name = "some")]
      public int RequestType { get; set; }
  }
  </code></pre>
  
  <p>my controller:</p>
  
  <pre><code>[HttpPost]
      [Authorize(Roles = "P")]
      public PartialViewResult ViewRequests(ViewRequestModel model)
      {
          string vn = "";
          switch (model.RequestType)
          {
              ...
          }
  
          return PartialView(vn);
      }
  </code></pre>
  
  <p>my view: </p>
  
  <pre><code>@{
      var reqTypes = new List&lt;ListItem&gt; { new ListItem { Text = "t1", Value = "1" }, 
         new ListItem { Text = "t2", Value = "2" },
         new ListItem { Text = "t3", Value = "3" } };
   }
   @Html.DropDownListFor(model =&gt; model.RequestType, new SelectList(reqTypes), new { id = "ddlType" })
  
   @Html.ValidationMessageFor(model =&gt; model.RequestType)
  </code></pre>
  
  <p>when I try to post my form, jquery validation blocks it and show the error <code>The field RequestType must be a number</code></p>
  
  <p>where's my mistake?</p>