如果我的Picker的SelectedIndex位于最后三个选项上而不是前两个选项上，我尝试将StackLayout Visibility设置为False。
以下是选取器的列表：

"1 - Yes",
"2 - No",
"97 - Don't Know",
"98 - No Answer",
"99 - Not Applicable"

XAML：

<!-- Intention to Use Family Planning --> 
<StackLayout Padding="10,0,10,10"> 
    <Label Text="Intention to use Family Planning?" 
           VerticalTextAlignment="Center" 
           FontAttributes="Bold"/> 
    <Border Padding="10,0,0,0"> 
        <StackLayout> 
            <Picker x:Name="PckIntentionFP" 
                    Title="Select a Family Planning Intention Option" 
                    ItemsSource="{Binding IntentionToFamilyPlanningItems}">
            </Picker>
        </StackLayout> 
    </Border> 
</StackLayout> 

<!-- Intention Yes/No -->
<StackLayout Padding="10,0,10,10">
    <StackLayout.Triggers>
        <MultiTrigger TargetType="StackLayout">
            <MultiTrigger.Conditions>
                <BindingCondition Binding="{Binding Source={x:Reference PckIntentionFP}, 
                                                    Path=SelectedIndex}" 
                                  Value="2"/>
                <BindingCondition Binding="{Binding Source={x:Reference PckIntentionFP}, 
                                                    Path=SelectedIndex}" 
                                  Value="3"/>
                <BindingCondition Binding="{Binding Source={x:Reference PckIntentionFP}, 
                                                    Path=SelectedIndex}"
                                  Value="4"/>
            </MultiTrigger.Conditions>
            <Setter Property="IsVisible" Value="False" />
        </MultiTrigger>
    </StackLayout.Triggers>
    <Label Text="If 'Yes', what method? If 'No', why not?"
           FontAttributes="Bold"
           VerticalTextAlignment="Center"/>
    <Frame Padding="10,0,10,0"
           Margin="5">
        <Entry VerticalOptions="Center"
               TextTransform="Uppercase"
               Text="{Binding LastName}">
        </Entry>
    </Frame>
</StackLayout>

这是我第一次在这里问问题，事先抱歉。
当我在平板电脑中运行应用程序时，当我选择最后三个选项时，它不会将StackLayout Visibility设置为False。
我真的很困惑，我可能错过了什么使用多触发器。