无法在应用中使用TimeSpanDisplay

Question

我是Windows Phone 7开发人员的新手。 我尝试本教程来创建一个秒表应用程序。 http://windowsphone7developerguide.blograby.com/stopwatch/

但是，输入此行时出现此错误

<local:TimeSpanDisplay x:Name=”TotalTimeDisplay” Grid.Row=”3”
Grid.ColumnSpan=”2” DigitWidth=”67”
HorizontalAlignment=”Center”
FontFamily=”Segoe WP Black” FontSize=”108” />

Error   1   The type 'local:TimeSpanDisplay' was not found. Verify that you are not missing an assembly reference and that all referenced assemblies have been built.   D:\New CS Job\Window Phone 7 Dev\Project\Stopwatch\Stopwatch\MainPage.xaml  35  10  Stopwatch

我尝试在谷歌中搜索我的错误但对我来说似乎没什么用。请帮帮我，我感到很沮丧。谢谢！