Unable to play unknown soundEvent

I started with java 1.8 recently and have gotten a problem with sounds.

everytime i try to start the sounds it says:

"Unable to play unknown soundEvent: mod:vs"

i dont think its in my sounds.json file (src/main/recourses/assets/mod/sounds/sounds.json):

{
"vs": {"category": "ambient","sounds": [{"name": "vs","stream": false}]}
}

and i've tried to run it with:

worldIn.playSoundAtEntity(playerIn, "mod:vs", 1.0F, 1.0F);