Reading, and displaying the value for [ChannelN],track_samples in skins

Hi, we can determine if a track is loaded into a deck by checking for [ChannelN],track_samples.
This works for controllers, but is this working in skins too?

I tried to archive the following:

Check if a track is loaded into a deck, and display a widget if [ChannelN],track_samples > 0.
In a first step i just try to display [ChannelN],track_samples in a label using the following code:

<Template>
  <SetVariable name="group">[Channel<Variable name="i"/>]</SetVariable>
  <SetVariable name="control_track_samples"><Variable name="group"/>,track_samples</SetVariable>
  <WidgetGroup>
    <ObjectName>foo</ObjectName>
    <Layout>horizontal</Layout>
    <SizePolicy>me,max</SizePolicy>
    <Children>
      <Label>
        <TooltipId>track_title</TooltipId>
        <Size>me,min</Size>
        <ObjectName>HiddenTrackTitleInfo</ObjectName>
        <Text><Variable name="control_track_samples"/></Text>
      </Label>
    </Children>
  </WidgetGroup>
</Template>

This does only partially work, since all i got was the output of the correct channel number + the track_samples string , i.e. ``[Channel1],track_samples``
The developer tools console reads instead: [Channel1],track_samples=25796736.00

Any clues?