waveOutOpen函数返回值是WAVERR_BADFORMAT？

m_waveformout.wFormatTag =WAVE_FORMAT_DSPGROUP_TRUESPEECH;//
m_waveformout.nChannels     =1;
m_waveformout.nSamplesPerSec =8000;//
m_waveformout.nAvgBytesPerSec   =8000;//
m_waveformout.nBlockAlign     =1;//
m_waveformout.wBitsPerSample =8;//32
m_waveformout.cbSize =20;//

MMRESULT mmr;
mmr = waveOutOpen(&hWaveOut,0,&m_waveformout,(DWORD)this->m_hWnd,NULL,CALLBACK_WINDOW);mmr等于WAVERR_BADFORMAT。什么地方有毛病？