It could be nothing, but I noticed that in your first (working) example of the Image
, you used this path to your image:
<Image Source="sample.png"></Image>
But the one that you say doesn't work is using this path:
<Image Source="img/sample.png"/>
Maybe that was just an error you made copying it here, but otherwise, try this in your ControlTemplate
:
<Image Source="sample.png"/>