In sounds, you have to be sensitive around this.
If you set the sound as a 3D sound, then you need to use trigger actions like:
Play Sound on Unit
Play Sound at Point
Play Sound From Offset
If you did not set the sound as a 3D sound, then use:
Play Sound
To check if you're using the sound as 3D sound, you can see it at Sound Properties when you already set its variable.
It is important to check the Min Distance if you set it as a 3D sound, because imported sounds mostly have this setting wrong, rendering the sound to be almost not heard. Set Min Distance to 600. Just to make sure, set your Distance Cutoff at 2100.