This is because your RadCoverFlowItem does not have a visual part to be clicked. Since you are using a StackPanel, your items are stacked inside the RadCoverFlowItem, and some parts of it are left without visual content. Make sure that you are actually clicking on the RadCoverFlowItem, for example you can set the background of the item to some distinct color in order to identify the visual presence of the item.
You can take a look at our CoverFlow DataInfo
examples that uses a special User Control to hold your template, and mouse click logic.
If you have any other questions, please feel free to contact us again.
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