ScaleTransform change Not work after Use Storyboard - wpf

Question

I change ScaleTransform with Storyboard and work fine, but after change ScaleTransform not work,
sample:
scaleTransform.ScaleX=1
after use Storyboard:
scaleTransform.ScaleX=2
when change in my code
scaleTransform.ScaleX += 1;
but scaleTransform.ScaleX=2,
private Storyboard _story = new Storyboard();
private void CreateAnimation(double x, double y, TimeSpan delay)
{
var stScaleX = new DoubleAnimation(scaleTransform.ScaleX, x, delay);
var stScaleY = new DoubleAnimation(scaleTransform.ScaleY, y, delay);
stScaleX.SetValue(Storyboard.TargetProperty, mainCanvas);
stScaleX.SetValue(Storyboard.TargetPropertyProperty, new PropertyPath("LayoutTransform.Children[0].ScaleX"));
stScaleY.SetValue(Storyboard.TargetNameProperty, mainCanvas.Name);
stScaleY.SetValue(Storyboard.TargetPropertyProperty, new PropertyPath("LayoutTransform.Children[0].ScaleY"));
_story.Children.Add(stScaleY);
_story.Children.Add(stScaleX);
mainCanvas.Resources.Clear();
_story.Changed += St_Changed;
_story.Completed += St_Completed;
_story.Begin(mainCanvas);
}
private void St_Completed(object sender, EventArgs e)
{
_story.Changed -= St_Changed;
_story.Completed -= St_Completed;
var newXy = new Point(_scalePoint.X, _scalePoint.Y);
scrollViewer.ScrollToHorizontalOffset(newXy.X);
scrollViewer.ScrollToVerticalOffset(newXy.Y);
var zs = GetScaleTransform(mainCanvas);
ZoomLevel = zs.ScaleX;
_story.Stop();
_story.Remove();
mainCanvas.Resources.Clear();
}
private void St_Changed(object sender, EventArgs e)
{
var newXy = new Point(_scalePoint.X, _scalePoint.Y);
scrollViewer.ScrollToHorizontalOffset(newXy.X);
scrollViewer.ScrollToVerticalOffset(newXy.Y);
}
private void mainCanvas_MouseWheel(object sender, MouseWheelEventArgs e)
{
var st = GetScaleTransform(mainCanvas);
var zoom = e.Delta > 0 ? .6 : -.6;
if (!(e.Delta > 0) && (st.ScaleX < .4 || st.ScaleY < .4))
return;
if (st.ScaleX <= 1 && zoom < 0) return;
var relativeOnImage = e.GetPosition(mainCanvas);
var relativeOnScreen = e.GetPosition(Grid1);
scaleTransform.ScaleX = st.ScaleX+zoom;
scaleTransform.ScaleY = st.ScaleY+ zoom;
if (st.ScaleX < 1) st.ScaleX = 1;
if (st.ScaleY < 1) st.ScaleY = 1;
var newSizeX = Grid1.ActualWidth*st.ScaleX;
newSizeX = ((newSizeX*relativeOnImage.X)/ Grid1.ActualWidth)- relativeOnScreen.X;
var newSizeY = Grid1.ActualHeight * st.ScaleY;
newSizeY = ((newSizeY*relativeOnImage.Y)/ Grid1.ActualHeight)- relativeOnScreen.Y;
scrollViewer.ScrollToHorizontalOffset(newSizeX);
scrollViewer.ScrollToVerticalOffset(newSizeY);
IsZooming = st.ScaleX > 1 || st.ScaleY > 1;
}

Answer 1

I sloved,
I change my code, and worked
var oldDataX = scaleTransform.ScaleX;
var oldDataY = scaleTransform.ScaleY;
scaleTransform.BeginAnimation(ScaleTransform.ScaleXProperty, null);
scaleTransform.BeginAnimation(ScaleTransform.ScaleYProperty, null);
scaleTransform.ScaleX = oldDataX + zoom;
scaleTransform.ScaleY = oldDataY + zoom;
for more information :
https://msdn.microsoft.com/en-us/library/aa970493(v=vs.90).aspx
http://www.codeproject.com/Tips/146505/WPF-Storyboard-animation-locks-properties-it-s-ani