 
     /// Get a new track
     public func newTrack(name: String = "Unnamed") -> AKMusicTrack? {
-        if isAVSequencer { return nil }
+        if isAVSequencer {
+            print("AVSequencer ERROR ! newTrack only work if not isAVSequencer ")
+            return nil }
 
         var newMusicTrack: MusicTrack = nil
         MusicSequenceNewTrack(sequence, &newMusicTrack)

            if isAVSequencer {
                return Double(avSequencer.rate)
            } else {
                return nil
            }
        }
        set {
            if isAVSequencer {
                avSequencer.rate = Float(newValue!)
            }
        }
    }

    ///
    public func setLoopInfo(duration: AKDuration, numberOfLoops: Int) {
        if isAVSequencer {
            print("AVSequencer ERROR ! setLoopInfo only work if not isAVSequencer ")

            //nothing yet
        } else {
            for track in tracks {
