Animation in CodeBehind just works once.

hey,

i've coded following Animation:

TextBlock block = child as TextBlock;
block.Visibility = Visibility.Visible;
animate = new ObjectAnimationUsingKeyFrames();
animate.FillBehavior = FillBehavior.HoldEnd;
animate.AutoReverse = false;
animate.Duration = new TimeSpan(0, 0, 0, 3);
DiscreteObjectKeyFrame kf1 = new DiscreteObjectKeyFrame(Visibility.Hidden, new TimeSpan(0, 0, 0, 3));
animate.KeyFrames.Add(kf1);
block.BeginAnimation(TextBlock.VisibilityProperty, animate);