title: Visibility binding fails
body: <p>I try to use the Visibility plugin with the FieldBinding plugin with no luck.</p>
  
  <p>Model side:</p>
  
  <pre><code>    /// &lt;summary&gt;
      /// Gets or sets the birthdate.
      /// &lt;/summary&gt;
      /// &lt;value&gt;
      /// The birthdate.
      /// &lt;/value&gt;
      public DateTime? Birthdate { get; set; }
  </code></pre>
  
  <p>ViewModel side:</p>
  
  <pre><code>public class DisplayUserViewModel : BaseUserViewModel
  {
      /// &lt;summary&gt;
      /// The user
      /// &lt;/summary&gt;
      public readonly INC&lt;User&gt; User = new NC&lt;User&gt;();
  }
  </code></pre>
  
  <p>View side, first try:</p>
  
  <pre><code>        &lt;RelativeLayout
              android:layout_width="wrap_content"
              android:layout_height="@dimen/ListIconTwoLineTileHeight"
              android:paddingRight="@dimen/ListIconTwoLineTextMarginRight"
              local:MvxBind="Visibility User.Birthdate, Converter=Visibility"&gt;
  </code></pre>
  
  <p>Second try:</p>
  
  <pre><code>        &lt;RelativeLayout
              android:layout_width="wrap_content"
              android:layout_height="@dimen/ListIconTwoLineTileHeight"
              android:paddingRight="@dimen/ListIconTwoLineTextMarginRight"
              local:MvxBind="Visibility Visibility(User.Birthdate)"&gt;
  </code></pre>
  
  <p>But same result:</p>
  
  <pre><code>MvxBind ( 2574):  33.60 Failed to create target binding for binding Visibility for MvxValueConverterValueCombiner combiner-operation
  </code></pre>
  
  <p>I just took the birthdate as an example, but every Visibility bindings failed (I have x error messages for x bindings).</p>
  
  <hr>
  
  <p><strong>EDIT 1</strong></p>
  
  <p>The others binding work, I bind a bunch of text, and all display well:</p>
  
  <pre><code>      &lt;TextView
           style="@style/TextView.ListWithIcon.Single"
           android:layout_marginTop="@dimen/ListIconTwoLineTextMarginTop"
           local:MvxBind="Text User.FirstName" /&gt;
  </code></pre>
  
  <p>I also try to bind to a INPC property, same result.</p>
  
  <hr>
  
  <p><strong>EDIT 2</strong></p>
  
  <p>As suggested by stuart, i tried this:</p>
  
  <pre><code>&lt;TextView
      style="@style/TextView.ListWithIcon.Single"
      android:layout_marginTop="@dimen/ListIconTwoLineTextMarginTop"
      android:layout_marginLeft="@dimen/ListIconTextMarginLeft"
      local:MvxBind="Text Visibility(User.Birthdate)"&gt;
  </code></pre>
  
  <p>And the visibility converter on TextView seems to work, if Birthdate is null:</p>
  
  <pre><code>Birthdate:  Gone
  </code></pre>
  
  <p>But it does not seem to bind to the visibility property:</p>
  
  <pre><code>&lt;TextView
      style="@style/TextView.ListWithIcon.SecondLine"
      android:layout_below="@+id/Birthday"
      local:MvxBind="Visibility Visibility(User.Birthdate)"
      android:text="Whatever birthdate" /&gt;
  </code></pre>
  
  <p>Displays "Whatever birthdate" whereas Visibility(User.Birthdate) returns Gone...</p>
  
  <hr>
  
  <p><strong>EDIT 3</strong></p>
  
  <p>If you use Visible pseudo-property everything works as expected.</p>
  
  <pre><code>&lt;RelativeLayout
              android:layout_width="wrap_content"
              android:layout_height="@dimen/ListIconTwoLineTileHeight"
              android:paddingRight="@dimen/ListIconTwoLineTextMarginRight"
              local:MvxBind="Visible User.Birthdate"&gt;
  </code></pre>