Uploading Files with ASP.Net MVC - get name but no file stream, what am I doing wrong?

I have this form in my view:

<!-- Bug (extra 'i') right here-----------v  -->
<!-- was: <form method="post" enctype="mulitipart/form-data" action="/Task/SaveFile"> -->
<form method="post" enctype="multipart/form-data" action="/Task/SaveFile">
<input type="file" id="FileBlob" name="FileBlob"/>
<input type="submit"  value="Save"/>
<input type="button" value="Cancel" onclick="window.location.href='/'" />
</form>

And this code in my controller:

public ActionResult SaveFile( FormCollection forms )
{
   bool errors = false;
   //this field is never empty, it contains the selected filename
   if ( string.IsNullOrEmpty( forms["FileBlob"] ) )
   {
       errors = true;
       ModelState.AddModelError( "FileBlob", "Please upload a file" );
   }
   else
   {
      string sFileName = forms["FileBlob"];
      var file = Request.Files["FileBlob"];
      //'file' is always null, and Request.Files.Count is always 0 ???
      if ( file != null )
      {
         byte[] buf = new byte[file.ContentLength];
         file.InputStream.Read( buf, 0, file.ContentLength );
         //do stuff with the bytes
      }
      else
      {
         errors = true;
         ModelState.AddModelError( "FileBlob", "Please upload a file" );
      }
   }
   if ( errors )
   {
      return ShowTheFormAgainResult(); 
   }
   else
   {
      return View();
   }
}

Based on every code sample I've been able to find, this seems like the way to do it. I've tried with small and large files, with no difference in the result. The form field always contains the filename which matches what I've chosen, and the Request.Files collection is always empty.

I don't think it's relevant, but I'm using the VS Development Web Server. AFAIK it supports file uploads the same as IIS.

It's getting late and there's a chance I'm missing something obvious. I'd be grateful for any advice.