SDK 4.0.6: Undefined symbol getStressHistory detected

Hi all, 

I believe I have this configured correctly, but when I build in VS Code with MonkeyC extension, I get error in the subject line. Stub code is below with error.  Followed example listed here Thoughts?

Thanks in advance,

Jeff

using Toybox.Sensor;
using Toybox.System;
using Toybox.Timer;
//for stress score
using Toybox.ActivityMonitor;

module Algorithms {
	class Sensor {
        //for stress score
		private var stressIterator;

		function start() {
			//start stress score iterator
			me.stressIterator = ActivityMonitor.getStressHistory(); //<---- this is where the error is reported
        }//function start()

    }//class
}//module