错误的错误代码

我portaudio用来播放声音。我希望能够通过UI选择输出。我这样管理：

PaError err = Pa_Initialize();
if( err != paNoError )
    return false;

qDebug() <<"Port audio succeed initialization !";

int numDevices;

numDevices = Pa_GetDeviceCount();
if( numDevices <= 0 )
{
    qDebug() << "ERROR: Pa_CountDevices returned " << numDevices;
    return false;
}

const PaDeviceInfo *deviceInfo;
bool isThereOutput = false;
int i = 0;
while(i < numDevices and !isThereOutput)
{
    deviceInfo = Pa_GetDeviceInfo( i );
    isThereOutput = (deviceInfo->maxOutputChannels > 0);
    i++;
}
if(!isThereOutput)
{
    qDebug() << "No output device";
    return false;
}

PaError errorOpening;

if(outputDevice != "")
{
    PaStreamParameters outputDeviceInfo;
    int numDevices = Pa_GetDeviceCount();

    const   PaDeviceInfo *deviceInfo;
    for(int i = 0; i<numDevices; i++ )
    {
        deviceInfo = Pa_GetDeviceInfo( i );
        if(deviceInfo->maxOutputChannels > 0 && deviceInfo->name == outputDevice)
        {
            outputDeviceInfo.device = i;
            outputDeviceInfo.channelCount = 1;
            outputDeviceInfo.sampleFormat = paInt8;
            outputDeviceInfo.suggestedLatency = deviceInfo->defaultLowOutputLatency;
        }
    }

    if(outputDeviceInfo.channelCount > 1)
    {
        errorOpening = Pa_OpenStream(&stream, NULL, &outputDeviceInfo, SAMPLE_RATE, FRAME_PER_BUFFER, paNoFlag, audioCallback, this);
    }

}

if(outputDevice == "" or errorOpening != paNoError)
{
    if(errorOpening != paNoError)
        qDebug() << "Can't open selected device ("<< outputDevice <<"), switching to the default one. Error : " << Pa_GetErrorText(errorOpening);
    errorOpening = Pa_OpenDefaultStream( &stream,
                      0,            /* no input channels */
                      1,            /* mono output */
                      paInt8,       /* 8 bits output */
                      SAMPLE_RATE,
                      FRAME_PER_BUFFER, /* frames per buffer, i.e. the number
                                              of sample frames that PortAudio will
                                              request from the callback. Many apps
                                              may want to use
                                              paFramesPerBufferUnspecified, which
                                              tells PortAudio to pick the best,
                                              possibly changing, buffer size.*/
                      audioCallback, /* this is your callback function */
                      this ); /*This is a pointer that will be passed to
                                                       your callback*/
}

if(errorOpening != paNoError)
    return false;

if(Pa_StartStream( stream ) != paNoError)
    return false;

它失败了：

无法打开所选设备（“ Sortieintégr”），切换到默认设备。错误：无效的错误代码（值大于零）

但是我不知道为什么会OpenStream失败，并显示一个奇怪的错误代码，并且Pa_OpenDefaultStream像魅力一样工作。

因此：

• 为什么会失败？
• 为什么会抛出错误的错误代码？