stageVideo on local Cam glitchy

Hi,

Actionscript3 / Flash version 32.0.330

When I'm using stageVideo for a local cam the video shown is blinking, repeating the same frames for ever.

rather, with a NetStream, everything is ok. Any clue?

var sv:Vector.<StageVideo> = stage.stageVideos;
stageVideo = sv[slotNumber];
if(stageVideo){
    stageVideo.addEventListener(StageVideoEvent.RENDER_STATE,onRenderStateChanged);
    gpuSlotArray[name] = slotNumber;
    if(isPublish == true){
         stageVideo.attachCamera(cam);
    }else{
        stageVideo.attachNetStream(ns);
    }

Thanks!