Help!Probleam when playing rtsp video

This probleam only happened on Nokia 308 & Nokia 311;
the video has shown but no voice,but I used browser to player the rtsp video is ok~
Fllowing is the implement code,my e-mail:cmmx207@163.com

public synchronized void initPlayer() {

try {
if (player == null) {
[COLOR="#FF0000"]//url like "rtsp://211.136.119.78/test/38hua.3gp"[/COLOR]
player = Manager.createPlayer(url);
}
if (player != null) {
player.addPlayerListener(this);
player.realize();
Control[] controls = player.getControls();
for (int i = 0; i < controls.length; i++) {
if (controls[i] instanceof VideoControl) {
videoC = (VideoControl) controls[i];
videoC.initDisplayMode(VideoControl.USE_DIRECT_VIDEO,
Display.getInstance().getCanvasImpl());
videoC.setDisplayLocation(videoX, videoY);
videoC.setDisplaySize(videoW, videoH);
videoC.setVisible(false);
}
if (controls[i] instanceof VolumeControl) {
volumeC = (VolumeControl) controls[i];
volumeLevel = volumeC.getLevel();
Util.writeLog("volumeLevel == "+volumeLevel, ""); //[COLOR="#FF0000"]value is 55 but there's no voice[/COLOR]
}
}
player.prefetch();
in_Player_State = PLAYER_STATE_DEVICE_PREPARE;
player.start();

setVisable(true);
in_Player_State = PLAYER_STATE_DEVICE_STARTED;
videoForm.showBufferLabel(Consts.FREEFEES,"initPlayer");
}
} catch (Exception e) {
closePlayer();
playerUpdate(null, PLAYEREXCEPTION, null);
}
}

I experienced similar thing: no sound on real Asha 305 device - but app works fine on SDK2.0 emulator...
My app tried to play sound clips only...

Is there any limitation to be aware of as app developer? E.g. supported audio file format - I use mp3 -, bit rate, size? Codec?
Can 'Too big' application size result in such weird behavior?

Specifications are available, you can find them under Devices above, Device specifications. Multimedia features are listed in the Multimedia group.
Application size is probably not a concern, if it is too large, the application can not be installed and started.

According to the specifications you mentioned, playing MP3 is supported feature - still no sound on real device...
Any idea is more than welcome...