Why am I not getting cadence?

Hi,

I'm trying to read the cadence in a Data Field app this way:

    showCadenceInsteadOfCalories = app.getProperty("c") && Sensor.Info has :cadence;
    ...

    if (showCadenceInsteadOfCalories) {
        cadence = Sensor.Info.cadence != null ? Sensor.Info.cadence : 0;
    }

but I only see 0 on my Forerunner 245 (and other Data Fields do display cadence)

What am I missing?