title: Multibinding Error
body: <p>I posted my question before:
  <a href="https://stackoverflow.com/questions/18129879/multi-forms-binding-data">Multi-Forms Binding data</a></p>
  
  <p>I solved it by building Converter.</p>
  
  <p>XAML:</p>
  
  <pre><code>&lt;Window x:Class="Test_MultiBinding.MainWindow"
          xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
          xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
          Title="MainWindow" Height="350" Width="621"
          xmlns:c="clr-namespace:Test_MultiBinding"&gt;
      &lt;Window.Resources&gt;
          &lt;c:myConverter x:Key="TestConverter"/&gt;
      &lt;/Window.Resources&gt;
  
      &lt;Grid&gt;
          &lt;TextBox TextWrapping="Wrap" AcceptsReturn="True" Height="269" HorizontalAlignment="Left" Margin="376,22,0,0" Name="textBox1" VerticalAlignment="Top" Width="211" &gt;
              &lt;TextBox.Text&gt;
                  &lt;MultiBinding Converter="{StaticResource TestConverter}"&gt;
                      &lt;Binding ElementName="textBox2" Path="Text"/&gt;
                      &lt;Binding ElementName="textBox3" Path="Text"/&gt;
                      &lt;Binding ElementName="textBox4" Path="Text"/&gt;
                      &lt;Binding ElementName="textBox5" Path="Text"/&gt;
                      &lt;Binding ElementName="textBox6" Path="Text"/&gt;
                  &lt;/MultiBinding&gt;
               &lt;/TextBox.Text&gt;
          &lt;/TextBox&gt;
          &lt;TextBox Height="40" HorizontalAlignment="Left" Margin="130,24,0,0" Name="textBox2" VerticalAlignment="Top" Width="222"/&gt;
          &lt;Button Content="Button" Height="23" HorizontalAlignment="Left" Margin="12,22,0,0" Name="button1" VerticalAlignment="Top" Width="75" Click="button1_Click" /&gt;
          &lt;TextBox Height="40" HorizontalAlignment="Left" Margin="130,70,0,0" Name="textBox3" VerticalAlignment="Top" Width="222" /&gt;
          &lt;TextBox Height="40" HorizontalAlignment="Left" Margin="130,116,0,0" Name="textBox4" VerticalAlignment="Top" Width="222" /&gt;
          &lt;TextBox Height="40" HorizontalAlignment="Left" Margin="130,162,0,0" Name="textBox5" VerticalAlignment="Top" Width="222" /&gt;
          &lt;TextBox Height="91" HorizontalAlignment="Left" Margin="130,208,0,0" Name="textBox6" VerticalAlignment="Top" Width="222" /&gt;
      &lt;/Grid&gt;
  &lt;/Window&gt;
  </code></pre>
  
  <p>MainWindow:</p>
  
  <pre><code>namespace Test_MultiBinding
  {
      public partial class MainWindow : Window
      {
          ......
      }
      [ValueConversion(typeof(string), typeof(string))]
      public class myConverter : IValueConverter
      {
          public Object Convert(object[] value, Type targettype, object parameter, System.Globalization.CultureInfo cultreinfo)
          {
              return str1 + value[0].ToString() + str2 + value[1].ToString() + str3 + value[2].ToString() + str4 + value[3].ToString() + str5 + value[4].ToString() + str6;
          }
  
          public Object ConvertBack(object value, Type targettype, object parameter, System.Globalization.CultureInfo cultreinfo)
          {
              throw new NotImplementedException();
          }
      }
  
  }
  </code></pre>
  
  <p>In which str1,2,3,... are string. When I run it, I got error:</p>
  
  <pre><code>An object of the type "Test_MultiBinding.myConverter" cannot be applied to a property that expects the type "System.Windows.Data.IMultiValueConverter"
  </code></pre>
  
  <p>Please help!</p>