toneAC v1.2 - Twice the volume, higher quality, higher frequency, etc.

This like a great library and is perfect for my needs, if only it worked...

On ATmega1284p (Dip)

The following code should make 10 tones, each with increasing volume, and a 0.2 second delay between each tone.

  for (byte volume=1; volume<=10; volume++) {
    toneAC (2000, volume, 500, false);
    delay (200);
  }

However, the volume isn't changing. The first 8 tones are identical, and then the last two tones (where volume is set to 9 and 10), it changes to a much higher frequency, but no change in volume.

Using ToneAC, V1.4