绑定功能区文本框IsEnabled复选框IsChecked不起作用

Here is the sample XAML:

以下是XAML示例:

...
<ribbon:RibbonTab Header="MyTab">
  <ribbon:RibbonGroup Header="Blah">
    <ribbon:RibbonTextBox x:Name="MyTextBox" 
                          IsEnabled="{Binding IsChecked, ElementName=MyCheckBox}" />
    <ribbon:RibbonCheckBox x:Name="MyCheckBox" Label="some text" />
  </ribbon:RibbonGroup>
</ribbon:RibbonTab>
...
...
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