What is wrong with this my hard disc serial number getting code?

BOOL GetDiskSerialNumber(std::wstring& wstSerialNumber, const TCHAR * wszPath)
{
    HANDLE hDevice = INVALID_HANDLE_VALUE;  // handle to the drive to be examined 
    BOOL bResult = FALSE;                 // results flag
    DWORD junk = 0;                     // discard results

    hDevice = CreateFileW(wszPath,          // drive to open
        0,                // no access to the drive
        FILE_SHARE_READ | // share mode
        FILE_SHARE_WRITE,
        NULL,             // default security attributes
        OPEN_EXISTING,    // disposition
        0,                // file attributes
        NULL);            // do not copy file attributes

    if (hDevice == INVALID_HANDLE_VALUE)    // cannot open the drive
    {
        return (FALSE);
    }

    STORAGE_PROPERTY_QUERY Query;
    Query.PropertyId = StorageAdapterSerialNumberProperty;
    Query.QueryType = PropertyStandardQuery;


    STORAGE_ADAPTER_SERIAL_NUMBER SNumber;
    //SNumber.Size = sizeof(STORAGE_ADAPTER_SERIAL_NUMBER);
    //SNumber.Version = sizeof(STORAGE_ADAPTER_SERIAL_NUMBER);

    bResult = DeviceIoControl(hDevice,                       // device to be queried
        IOCTL_STORAGE_QUERY_PROPERTY, // operation to perform
        &Query, sizeof(Query),                       // no input buffer
        &SNumber, sizeof(SNumber),            // output buffer
        &junk,                         // # bytes returned
        (LPOVERLAPPED)NULL);          // synchronous I/O

    CloseHandle(hDevice);
    DWORD dwLastError;
    if (!bResult)
    {
        dwLastError = GetLastError();
    }
    wstSerialNumber = SNumber.SerialNumber;

    return (bResult);
}