Hi all, I am trying to implement an audio play and record application using Vista new WASAPI for my audio WaveRT audio driver. When i am playing or recording in AUDCLNT_SHAREMODE_SHARED mode it working fine (with max latency 8 ms). To minimize the latency I want to use AUDCLNT_SHAREMODE_EXCLUSIVE mode for playing and recording, but it does not work if I specify AUDCLNT_STREAMFLAGS_EVENTCALLBACK flag. hr = pAudioClient->Initialize( AUDCLNT_SHAREMODE_EXCLUSIVE, AUDCLNT_STREAMFLAGS_EVENTCALLBACK, hnsRequestedDuration, hnsRequestedDuration, &wfx, NULL); Without this EVENT CALLBACK the Initialize succeed. I am using Vista SP1 as a client. Is there anything we have to do special in the WaveRT driver -- Or I have do something in my application? I have no idea what is going wrong. F.Y.I This WaveRT driver works fine with WaveXXX legacy APIs with Please help. Thanks in advance, Chandan