SDL混音器声音未播放

我正在使用SDL制作一个游戏,但我的SoundHandler类不起作用,我不知道为什么。文件路径是绝对正确的,我已经正确设置了SDL_Mixer,因为我以前有正确的声音工作,我也没有收到错误或警告,游戏运行良好,只是没有音乐。

声音处理程序.h:

enum Sounds
{
    BACKGROUND_MUSIC, STICK_COLLECT
};

class SoundHandler
{
    public:
        SoundHandler();
        void PlaySound(Sounds sound);
    private:
        Mix_Music *backMusic;
        Mix_Music *stickCollect;
};

声音处理程序.cpp:

SoundHandler::SoundHandler()
{
    Mix_OpenAudio(22050, MIX_DEFAULT_FORMAT, 2, 4096);
    this->backMusic = Mix_LoadMUS("Data//Music//Background.mp3");
    this->stickCollect = Mix_LoadMUS("Data//Sounds//StickCollect.mp3");
    Mix_VolumeMusic(128);
}

void SoundHandler::PlaySound(Sounds sound)
{
    if(sound == BACKGROUND_MUSIC)
    {
        Mix_PlayMusic(this->backMusic, -1);
    }
    if(sound == STICK_COLLECT)
    {
        Mix_PlayMusic(this->stickCollect, 1);
    }
}

main.cpp中的相关行:

// Initialise Sound
SoundHandler soundHandler;

// Play Background Music
soundHandler.PlaySound(BACKGROUND_MUSIC);

// Play Sound
soundHandler.PlaySound(STICK_COLLECT);