在dragenter上设置tabItem的动画

我试图在我的tabcontrol中创建一个效果,当拖动到一个选项卡上时,我想将其向右移动x个像素,在拖动时创建一个滑动效果,但我似乎无法启动动画。我错过了什么:

                       <Style TargetType="{x:Type TabItem}">                               
                            <Setter Property="RenderTransform">
                                <Setter.Value>
                                    <TransformGroup>
                                        <RotateTransform />
                                        <TranslateTransform />
                                        <SkewTransform />
                                        <ScaleTransform />
                                    </TransformGroup>
                                </Setter.Value>
                            </Setter>
                            <Setter Property="Template">
                            <Setter.Value>
                                <ControlTemplate TargetType="{x:Type TabItem}">
                                    <ControlTemplate.Triggers>
                                        <EventTrigger RoutedEvent="TabItem.DragEnter" >
                                            <BeginStoryboard>
                                                <Storyboard>
                                                    <DoubleAnimation 
                                                         Storyboard.TargetProperty="(TabItem.RenderTransform).(TranslateTransform.X)"
                                                         From="0"
                                                         To="50"
                                                         Duration="0:0:0.5"
                                                         FillBehavior="Stop"/>
                                                </Storyboard>
                                            </BeginStoryboard>
                                        </EventTrigger>
                                    </ControlTemplate.Triggers>
                                </ControlTemplate>
                            </Setter.Value>
                        </Setter>