[JAVA3D] A strange problem

[Chaohui Zhu]

Hi, everyone,   I met with a strange problem today, see following code:         BranchGroup br = new BranchGroup();       MediaContainer mediacontainer = loadSoundFile("background.wav");       BackgroundSound backgroundsound = new BackgroundSound(mediacontainer, 1.0f);         TransformGroup tg = new TransformGroup();          tg.setCapability(TransformGroup.ALLOW_TRANSFORM_READ);          tg.setCapability(TransformGroup.ALLOW_TRANSFORM_WRITE);       tg.addChild(backgroundsound);       br.addChild(tg);   I don't know why the system always warns me: javax.media.j3d.RestrictedAccessException: Group: only a BranchGroup node may be added.     Anyone can help me to solve this problem? It will help me much.         Best regards,       Chaohui