scale animation issue

Hi, I do simple animation for custom tree item element. Problem is in a part of scale animation. Here the code describing style.

<Style.Triggers><EventTrigger RoutedEvent="TreeViewItem.Loaded"><BeginStoryboard><Storyboard><DoubleAnimationUsingKeyFrames Storyboard.TargetProperty="(UIElement.RenderTransform).(TransformGroup.Children)[0].(ScaleTransform.ScaleX)"><EasingDoubleKeyFrame KeyTime="0" Value="0.5"/><EasingDoubleKeyFrame KeyTime="0:1:5" Value="1"/></DoubleAnimationUsingKeyFrames><DoubleAnimationUsingKeyFrames Storyboard.TargetProperty="(UIElement.RenderTransform).(TransformGroup.Children)[0].(ScaleTransform.ScaleY)"><EasingDoubleKeyFrame KeyTime="0" Value="0.5"/><EasingDoubleKeyFrame KeyTime="0:1:5" Value="1"/></DoubleAnimationUsingKeyFrames></Storyboard></BeginStoryboard></EventTrigger></Style.Triggers>

And then exception is occur: Property "[Unknown]" didnt point to DependencyObject in path "(0).(1)[0].(2)".

Animated tree view item consist of the following objects: labels, paths, image.

Aleksey