Channelgroup is not working

here is my script:
var instance = RuntimeManager.CreateInstance(eventName);
instance.getChannelGroup(out ChannelGroup group);

the result is Volume can’t change. but if i use [getMasterChannelGroup] and set Volume it work.
can anyone help?

Can I please grab a little more info?
Are you doing all of this in Start()?
I found calling getChannelGroup immediately after CreateInstance inside Start() meant that the ChannelGroup hadn’t been created yet.
I suggest you check the FMOD.RESULT, which gives you useful information after an API call. This should let you know whether the instance is being created correctly and if there are any issues with the group.

yes, i calling getChannelGroup after Start(),it works, thank you very much!!