Strange Error

Hi,

I have coded this:

sing Toybox.Application    as App;
using Toybox.WatchUi        as Ui;
using Toybox.Background;

(:background)
class BatteryInfoApp extends App.AppBase {

    function initialize() {
        AppBase.initialize();
    	
    	var batData = new batteryData();
    }
}

As soon as I compile this I get an Error:

Error: Illegal Access (Out of Bounds)
Details: Failed invoking <symbol>
Stack:
- initialize() at BatteryInfoApp.mc:21 0x1000001f

It addresses the line with the new batteryData().

I used this statement thousand of times before and I have no clue why this error is thrown. Any hints?