Audio capture start time always to 0

1
Hi,

I am trying to use the voice trigger for reaction time calculation, but startTime or tCaptureStart are always 0 when i use
startTime = PsychPortAudio('Start', pahandle, 0, 0, 1); or
[audiodata offset overflow tCaptureStart] = PsychPortAudio('GetAudioData', pahandle);
I tried both non-low-latency and low-latency sound drivers.
Anybody faced this problem before?

OS:Windows XP Pro SP3

Romain