将IsChecked属性设置为true / false不会触发wpf中的已检查/未检查事件

Question

我有以下代码。当PlayVideoState值设置为true / false时，不会触发任何已检查/未选中的事件。什么遗失？请建议。

<CheckBox Style="{DynamicResource PlayButton}" Margin="6" Name="PlayButton" IsChecked="{Binding _Extensions.PlayVideoState, Mode=TwoWay}">
                    <i:Interaction.Triggers>
                        <i:EventTrigger EventName="Checked">
                            <ei1:GoToStateAction StateName="VideoOn"/>
                        </i:EventTrigger>
                        <i:EventTrigger EventName="Unchecked">
                            <ei1:GoToStateAction StateName="VideoOff"/>
                        </i:EventTrigger>
                    </i:Interaction.Triggers>
                    <TextBlock x:Name="textBlock2" FontFamily="{DynamicResource FontFamily1}" Foreground="{DynamicResource Text01}" Margin="0" VerticalAlignment="Center" FontSize="21.333"><Run Language="en-gb" Text="Video"/></TextBlock>
                </CheckBox>