Habpanel url location

I started with habpanel template.
I want to interact with a directory where I store some images
This is the code

  <div class="col-xs-4 modgrid">
     <button class="sonosbutton" style="background-image: url(/static/sonos/radio2.PNG); background-size: contain; background-repeat: no-repeat;background-position: center center" 
        ng-click="sendCmd('SonosPlay1BadkamerRadio', 'NPO Radio 2 92.9 (Pop)')">

I have stored the file radio2.PGN on my NAS where openhab is running on in this directory /SmartHome/openHAB/static/sonos

Problem is the file is not shown so I assume the location is wrong.
Can someone help with this.