Please help me understand RTMP dynamic streaming

Question

Hello all,
I am using rtmp dynamic streaming loading my video files from Amazon Cloudfront and the videos load and play, however the stream never dynamically switches from the initial Index setting. 
I am setting up my media player object with:
mediaPlayer = new MediaPlayer();
mediaPlayer.addEventListener(TimeEvent.CURRENT_TIME_CHANGE, updateTime);
mediaPlayer.addEventListener(TimeEvent.COMPLETE, onDone);
mediaPlayer.addEventListener(DynamicStreamEvent.AUTO_SWITCH_CHANGE, onAutoChange);
mediaPlayer.addEventListener(DynamicStreamEvent.SWITCHING_CHANGE, onChange);
mediaPlayer.addEventListener(MediaPlayerStateChangeEvent.MEDIA_PLAYER_STATE_CHANGE, onStateChange);
mediaPlayer.loop = false;
mediaPlayer.autoDynamicStreamSwitch = true;
mediaPlayer.bufferTime = 2;
mediaPlayer.autoRewind = false;
I am also setting up my media element :
var bitrates:XMLList = vid.videoEncodes.videoEncode;
var resource:DynamicStreamingResource = new DynamicStreamingResource(vid.@server + "_definst_");
var vector:Vector.<DynamicStreamingItem> = new Vector.<DynamicStreamingItem> (bitrates.length());
for(var i:Number = 0; i < bitrates.length(); i++){
vector[i] = (new DynamicStreamingItem("MP4:" + FILENAME, BITRATE));
resource.streamItems = vector;
resource.initialIndex = 0;
var videoElement:VideoElement = new VideoElement(resource);
videoElement.smoothing = true;
videoElement.deblocking = 0;
My video files have the keyframes set at 2 seconds apart. And have 4 bitrate file options, 400, 700,1000,1300.  But, as mentioned above the player starts on the initial index and stays there.  What am I doing wrong?
Thanks

Answer 1

and, the onchange function does this:
public function onChange(e:DynamicStreamEvent):void{
if(e.switching){
trace("Change Request");
}else{
trace("CHANGE - " + mediaPlayer.currentDynamicStreamIndex + " " + mediaPlayer.maxAllowedDynamicStreamIndex + " " + "Current bitrate = " + mediaPlayer.getBitrateForDynamicStreamIndex(mediaPlayer.currentDynamicStreamIndex) + "kbps");
the trace always shows me 3 as the maxallowed, and 400 as my currentBitrate