D2Air missing "next()" for iterator.

My app downloads courses. It works on the D2Charlie but not on the D2Air. This is in the simulator.

The app throws a "Symbol not found" at the "next()" call.

else if(!(data instanceof Toybox.PersistedContent.Iterator))
{
    bError = true;

    System.println("data not course/track.");
    appbase.strStatus = "No course/track returned. ";
}
else
{
    var item;
    intCountCoursesInFile = 0;

    while (data != null)
    {
        item = data.next(); // FAILS with "Error: Symbol Not Found Error"

        if (item == null)
        {
            break;
        }
    }
}