enableTabCaptureAPI is not working

[zenlykoi]

My code in here

var recorder = new RecordRTC_Extension();
recorder.startRecording({
	enableTabCaptureAPI: true,
    enableTabCaptureAPIAudioOnly: false
}, function() {
    setTimeout(function() {
        recorder.stopRecording(function(blob) {
            console.log(URL.createObjectURL(blob))
        });
    }, 5000);
});

I inject mycode to a website to record sound and screen in this website same as 'chrome tab' option in extension. But it sometimes successful, sometimes unsuccessful.

[Minimalpris]

any news here?