Failed invoking <symbol> trying to read torque efectiveness

Hello:

I'm trying to read the torque effectiveness for a data field and I get the error Failed invoking <symbol>

First of all I declared the class

using Toybox.WatchUi as Ui;
using Toybox.Graphics as Gfx;
using Toybox.UserProfile as Upf;
using Toybox.Application as App;
using Toybox.AntPlus as Apl;

class MyBikePowerListener extends Apl.BikePowerListener
{
    //Initializes class variables
    function initialize()
    {
        Apl.BikePowerListener.initialize();
    }
}

Then, inside the function initialize() of my class that extends the Ui.DataField I have

var listener = new MyBikePowerListener();
var bikePower = new Apl.BikePower(listener);

And then inside my function compute(info) I have

var torqueData = bikePower.getTorqueEffectivenessPedalSmoothness();

Until here the code works. If I simulate data from the wizard all works well. But the problem comes when I try to extract the data as

var data_left = torqueData.leftTorqueEffectiveness;

If I put this code I obtain the Failed invoking <symbol>. Obviously I'm doing something wrong, but I can't find the source. Could anyone help, please? Or maybe someone could share some code about reading these advanced power metrics?

Thanks