Tap Gesture event not firing on children of stackpanel which is in SurfaceScrollViewer wpf

hi all,

I wants to fire Tap Gesture Event on Images inside StackPanel but it's not firing & other events likePreviewTouchDown is firing plese help me.

<s:SurfaceScrollViewer x:Name="scrollviewewrContainer" HorizontalScrollBarVisibility="Hidden" VerticalScrollBarVisibility="Disabled"   PanningMode="HorizontalOnly"   ><StackPanel x:Name="stackImage" Orientation="Horizontal"  CanHorizontallyScroll="True" ><Image Source="Resources/Images/left_arrow.png" /><Image Source="Resources/Images/right_arrow.png"/></StackPanel></s:SurfaceScrollViewer>