title: Unable to combine tags using TagBuilder
body: <p>I'm trying to build a combination tag:</p>
  
  <p>First tag: <code>&lt;span class="requiredInidicator"&gt;* &lt;/span&gt;</code>
  Second tag: <code>&lt;label&gt;SomeText&lt;/label&gt;</code> (Attributes snipped for brevity)</p>
  
  <p>I would like to combine these to return an MVCHtmlString but the following code ignores the span completely. Could someone point out
  what I am doing wrong</p>
  
  <p>Here is my code:</p>
  
  <pre><code>// Create the Label
  var tagBuilder = new TagBuilder("label");
  tagBuilder.Attributes.Add("id", "required" + id);
  //I get the id earlier fyi - not pertinent fyi for this question )
  
  // Create the Span
  var required = new TagBuilder("span");
  required.AddCssClass("requiredInidicator"); 
  required.SetInnerText("* ");
  
  //Now combine the span's content with the label tag
  tagBuilder.InnerHtml += required.ToString(TagRenderMode.Normal);
  tagBuilder.SetInnerText(labelText);
  var tag = MvcHtmlString.Create(tagBuilder.ToString(TagRenderMode.Normal));
  return tag;
  </code></pre>
  
  <p>When the tag is created, the <em>span</em> is ignored completely. When I inspect the tag during debug, it doesn't care about the required that I appended via <code>.InnerHtml+=</code></p>
  
  <p>Is there something obvious I am doing wrong?</p>