meteor livestamp with reactive-table

I have a meteor app using livestamp. However, I wish to represent a collection within a reactive-table. However, when I try the code below, it doesn't work (I see nothing in the updated column):

Template.sensor_table.helpers
  settings: () ->
    return {
      collection: Sensors
      rowsPerPage: 100
      showFilter: true
      fields: [ 
        { key: '_id', label: 'id' },
        { key: '_id', label: 'rack', fn: (v,o) -> (getSensor v).rack },
        { key: 'temp', label: 'temperature (degC)' },
        { key: 'ts', label: 'updated', fn: (v,o) -> livestamp v }
      ]
    }

but when I use it within a template, it works fine. How can I get the functionality of livestamp within my reactive table?

so i guess it helps to actually read the manual....

Template.sensor_table.helpers
  settings: () ->
    return {
      collection: Sensors
      rowsPerPage: 100
      showFilter: true
      fields: [ 
        { key: '_id', label: 'id' },
        { key: '_id', label: 'rack', fn: (v,o) -> (getSensor v).rack },
        { key: 'temp', label: 'temperature (°C)' },
        { key: 'ts', label: 'updated', tmpl: Template.sensor_updated }
      ]
    }

and then a template somewhere...

<template name="sensor_updated">
{{ livestamp ts }}
</template>