在我开始解决问题之前，我想说我对编程非常陌生，所以如果您的答案具体，我会非常感激。
我将Silverlight Toolkit（2011年11月）添加到我的Visual Studio 2010 Express for Windows Phone中。我已将.dll添加到参考中。
我在我的应用程序中使用了TimePicker工具。但是，当我运行它时，我收到一个错误：
"Invalid attribute value controls:LongListSelector for property TargetType. [Line: 440 Position: 12]"
在网上搜索这个问题之后，给出的大部分答案都是将其添加到xaml：
xmlns:controls="clr-namespace:Microsoft.Phone.Controls;assembly=Microsoft.Phone.Controls.Toolkit"
那条线已经在我的xaml中了，但最后它只说了"...Microsoft.Phone.Controls"。所以我刚刚添加了.Toolkit"
但错误仍然存在。 MainPage.g.i.cs中突出显示以下行：
System.Windows.Application.LoadComponent(this, new System.Uri("/WindowsPhoneApplication1;component/MainPage.xaml", System.UriKind.Relative));
顺便说一下，我刚才意识到已经有了另一个带有相同代码的前缀，即xmlns:toolkit="clr-namespace:Microsoft.Phone.Controls;assembly=Microsoft.Phone.Controls.Toolkit"
所以现在我已经将'controls'前缀更改为xmlns:controls="clr-namespace:Microsoft.Phone.Controls;assembly=Microsoft.Phone.Controls"
但错误仍然存在。
<phone:PhoneApplicationPage
x:Class="WindowsPhoneApplication1.MainPage"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:phone="clr-namespace:Microsoft.Phone.Controls;assembly=Microsoft.Phone"
xmlns:shell="clr-namespace:Microsoft.Phone.Shell;assembly=Microsoft.Phone"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
mc:Ignorable="d" d:DesignWidth="480" d:DesignHeight="768"
FontFamily="{StaticResource PhoneFontFamilyNormal}"
FontSize="{StaticResource PhoneFontSizeNormal}"
Foreground="{StaticResource PhoneForegroundBrush}"
SupportedOrientations="Portrait" Orientation="Portrait"
shell:SystemTray.IsVisible="True"
xmlns:toolkit="clr-namespace:Microsoft.Phone.Controls;assembly=Microsoft.Phone.Controls.Toolkit"
xmlns:controls="clr-namespace:Microsoft.Phone.Controls;assembly=Microsoft.Phone.Controls">
<!--LayoutRoot is the root grid where all page content is placed-->
<Grid x:Name="LayoutRoot" Background="Transparent">
<Grid.RowDefinitions>
<RowDefinition Height="Auto"/>
<RowDefinition Height="*"/>
</Grid.RowDefinitions>
<!--TitlePanel contains the name of the application and page title-->
<StackPanel x:Name="TitlePanel" Grid.Row="0" Margin="12,17,0,28">
<TextBlock x:Name="ApplicationTitle" Text="MY APPLICATION" Style="{StaticResource PhoneTextNormalStyle}"/>
<TextBlock x:Name="PageTitle" Text="page name" Margin="9,-7,0,0" Style="{StaticResource PhoneTextTitle1Style}"/>
</StackPanel>
<!--ContentPanel - place additional content here-->
<Grid x:Name="ContentPanel" Grid.Row="1" Margin="12,0,12,0">
<Button Content="Refresh" Height="71" HorizontalAlignment="Left" Margin="309,60,0,0" Name="buttonRefresh" VerticalAlignment="Top" Width="141" Click="button1_Click" />
<TextBlock Height="35" HorizontalAlignment="Left" Margin="47,28,0,0" Name="textBlock1" Text="Current time:" VerticalAlignment="Top" Width="132" TextWrapping="Wrap" />
<TextBlock Height="47" HorizontalAlignment="Left" Margin="47,70,0,0" Name="textBlockCurrentTime" Text="Press Refresh to view" VerticalAlignment="Top" Width="251" FontSize="25" DataContext="{Binding}" FontFamily="Segoe WP" Foreground="#FF05BFFF" Opacity="1" IsHitTestVisible="True" />
<TextBox HorizontalAlignment="Left" Margin="53,276,0,251" Name="textBoxHour" Text="0" Width="101" FontSize="20">
<TextBox.InputScope>
<InputScope>
<InputScopeName NameValue="TelephoneNumber" />
</InputScope>
</TextBox.InputScope>
</TextBox>
<TextBox Height="80" HorizontalAlignment="Left" Margin="174,276,0,0" Name="textBoxMin" Text="0" VerticalAlignment="Top" Width="101" FontSize="20">
<TextBox.InputScope>
<InputScope>
<InputScopeName NameValue="TelephoneNumber" />
</InputScope>
</TextBox.InputScope>
</TextBox>
<TextBox Height="80" HorizontalAlignment="Right" Margin="0,276,70,0" Name="textBoxSec" Text="0" VerticalAlignment="Top" Width="101" FontSize="20">
<TextBox.InputScope>
<InputScope>
<InputScopeName NameValue="TelephoneNumber" />
</InputScope>
</TextBox.InputScope>
</TextBox>
<TextBlock Height="33" HorizontalAlignment="Left" Margin="63,349,0,0" Name="textBlock2" Text="Hours" VerticalAlignment="Top" Width="91" />
<TextBlock Height="33" HorizontalAlignment="Left" Margin="184,349,0,0" Name="textBlock3" Text="Min" VerticalAlignment="Top" Width="91" />
<TextBlock Height="33" HorizontalAlignment="Right" Margin="0,349,70,0" Name="textBlock4" Text="Sec" VerticalAlignment="Top" Width="91" />
<TextBlock Height="109" HorizontalAlignment="Left" Margin="70,460,0,0" Name="textBlockResult" Text="Press Add" VerticalAlignment="Top" Width="310" FontSize="30" />
<Button Content="Add" Height="72" HorizontalAlignment="Left" Margin="138,381,0,0" Name="buttonAdd" VerticalAlignment="Top" Width="160" Click="buttonAdd_Click" />
<toolkit:TimePicker HorizontalAlignment="Left" Margin="47,197,0,0" Name="timePickerCustomTime" VerticalAlignment="Top" Height="73" Width="273" IsEnabled="False" />
<CheckBox Content="Use custom time" Height="73" HorizontalAlignment="Left" Margin="53,123,0,0" Name="checkBoxCustomTime" VerticalAlignment="Top" Width="245" />
</Grid>
</Grid>
<!--Sample code showing usage of ApplicationBar-->
<!--<phone:PhoneApplicationPage.ApplicationBar>
<shell:ApplicationBar IsVisible="True" IsMenuEnabled="True">
<shell:ApplicationBarIconButton IconUri="/Images/appbar_button1.png" Text="Button 1"/>
<shell:ApplicationBarIconButton IconUri="/Images/appbar_button2.png" Text="Button 2"/>
<shell:ApplicationBar.MenuItems>
<shell:ApplicationBarMenuItem Text="MenuItem 1"/>
<shell:ApplicationBarMenuItem Text="MenuItem 2"/>
</shell:ApplicationBar.MenuItems>
</shell:ApplicationBar>
</phone:PhoneApplicationPage.ApplicationBar>-->