title: RadioButtonList exception
body: <p>After I upgraded to the beta, I'm having trouble with Html.RadioButtonList.  Can someone show me what I'm doing wrong?</p>
  
  <p>The code:</p>
  
  <pre><code>&lt;% Html.RadioButtonList(
      "voter" + voter.Id,
      new SelectList(new[]{"yes","no","abstain"}, "yes")).Each(x =&gt; Response.Write(x)); %&gt;
  </code></pre>
  
  <p>And the exception I get:</p>
  
  <pre><code>[ArgumentNullException: Value cannot be null.
  Parameter name: value]
     System.Web.Mvc.Html.InputExtensions.RadioButton(HtmlHelper htmlHelper, String name, Object value, Boolean isChecked, IDictionary`2 htmlAttributes) +214
     Microsoft.Web.Mvc.&lt;&gt;c__DisplayClass1.&lt;RadioButtonListInternal&gt;b__0(ListItem item) in c:\dd\Cicero\src\Mvc\main\src\MvcFutures\Mvc\RadioExtensions.cs:86
     System.Linq.WhereSelectListIterator`2.MoveNext() +107
     System.Linq.Buffer`1..ctor(IEnumerable`1 source) +259
     System.Linq.Enumerable.ToArray(IEnumerable`1 source) +81
     Microsoft.Web.Mvc.RadioListExtensions.RadioButtonListInternal(HtmlHelper htmlHelper, String name, SelectList selectList, Boolean usedViewData, IDictionary`2 htmlAttributes) in c:\dd\Cicero\src\Mvc\main\src\MvcFutures\Mvc\RadioExtensions.cs:88
     Microsoft.Web.Mvc.RadioListExtensions.RadioButtonList(HtmlHelper htmlHelper, String name, SelectList selectList) in c:\dd\Cicero\src\Mvc\main\src\MvcFutures\Mvc\RadioExtensions.cs:29
  </code></pre>
  
  <p>Many thanks in advance!<br>
  Rob </p>