大家来看看pviot控件的问题

[nice_wp]

为什么这串代码放到普通视图里有用，放到pviot里面却不行呢，求解决方式
<controls:PivotItem Header="正在下载"/>
<!--<TextBlock Text="you have no transfers registered" Name="EmptyTextBlock" Visibility="Collapsed"/>
<ListBox Name="TransferListBox">
<ListBox.ItemTemplate>
<DataTemplate>
<Grid Background="Transparent" Margin="0,0,0,30">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="380"/>
<ColumnDefinition Width="50"/>
</Grid.ColumnDefinitions>
<Grid Grid.Column="0">
<StackPanel Orientation="Vertical">
<TextBlock Text="{Binding Tag}" Foreground="{StaticResource PhoneAccentBrush}" FontWeight="Bold"/>
<StackPanel Orientation="Horizontal">
<TextBlock Text="status: "/>
<TextBlock Text="{Binding TransferStatus}" HorizontalAlignment="Right"/>
</StackPanel>
<StackPanel Orientation="Horizontal">
<TextBlock Text="bytes received:"/>
<TextBlock Text="{Binding BytesReceived}" HorizontalAlignment="Right"/>
</StackPanel>
<StackPanel Orientation="Horizontal">
<TextBlock Text="total bytes:"/>
<TextBlock Text="{Binding TotalBytesToReceive}" HorizontalAlignment="Right"/>
</StackPanel>
</StackPanel>

</Grid>
<Grid Grid.Column="1">
<Button Tag="{Binding RequestId}" Click="CancelButton_Click" Content="X" BorderBrush="Red" Background="Red" Foreground="{StaticResource PhoneBackgroundBrush}" VerticalAlignment="Top" BorderThickness="0" Width="50" Padding="0,0,0,0"></Button>
</Grid>
</Grid>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>-->