C# system.createChannel() returmed 'ERR_INVALID_PARAM'

FMOD Engine
1 
private void FmodERRCheck(Fmod.RESULT result){
    if (result != RESULT.OK)
    {
        MessageBox.Show(Fmod.Error.String(result));
    }
}

private void InitFmodSystems()
{
    Fmod.Factory.System_Create(out system);
    system = new Fmod.System(IntPtr.Zero);
    system.init(3, INITFLAGS.NORMAL, IntPtr.Zero);

    channelGroup = new ChannelGroup(IntPtr.Zero);

    FmodERRCheck(system.createChannelGroup(null, out channelGroup));
}

Hi there this time I get unknown error. in c++, when invoke playSound() function we can be replace ChannelGroup value to 0 or FREE. but C#'s example not exist every website. so I can't coding with compare to c++ codes what's wrong in this case?
2

Can you confirm the system_create and system.init both return FMOD_OK?

3

Cameron Baron Sorry man, i was so foolish xDDD
I’m trying to construct after System_Create. Ha-Ha
so system instance be baby.