Legacy GM why audio track is not 'fading in' but starts at full volume

[jobjorgos]

I have this in the create event:

audio_play_sound(snd_xmas_song,10,true);
audio_sound_gain(snd_xmas_song,0,0);
audio_sound_gain(snd_xmas_song,1,10000);

But the song starts instantly at full volume, why and how can I prevent that?

 

[jobjorgos]

I discovered now the fading in of the volume works if I do this:

Create:

audio_play_sound(snd_xmas_song,10,true);
audio_sound_gain(snd_xmas_song,0,0);
//audio_sound_gain(snd_xmas_song,1,10000);
alarm[0]=2;

Alarm[0]:

audio_sound_gain(snd_xmas_song,1,10000);

Beside the fact this is a solution, I still find it strange why it cant be done in just one single event in a single step/frame?
It is more work to make for every track an extra alarm every time...