Minecraft not recognizing Datapack

I'm trying to make a Datapack that changes the In-game advancements, but the Datapack isn't showing up in the Datapack menu in world creation, or in /datapack list.
Advancements+\data\minecraft\advancement\minecraft
{
    "pack": {
        "pack_format": 71
        "description": "Advancement test"
    }
}
Is there anything obviously wrong with my Datapack?