discord.py on_member_join ne fonctionne pas @ bot.event

Voici mon code pour un robot discord. J'essaye de lui faire changer le nom du serveur en nombre de membres dans le serveur. J'ai regardé cet exemple mais cela n'a pas fonctionné. Quelqu'un peut-il aider? Je ne reçois aucune erreur et ma sortie est également ci-dessous. Quand j'essaye d'ajouter le @ bot.event pour on_member_join, il ne semble même pas y arriver.

Production

import discord
import json
import asyncio
from discord.ext.commands import Bot
import aiohttp
from discord.utils import get
import json
from settings import bots
import pyjokes


TOKEN = open("token.txt").readlines()[0].strip()
prefix = "~"
bot = Bot(command_prefix=prefix, description="Ready to serve!")

# Runs when the bot is activated
@bot.event
async def on_ready():
    print('Logged in as')
    print(bot.user.name)
    print(bot.user.id)
    print('------')
    print(discord.utils.oauth_url(bot.user.id))

# @bot.event
# async def on_member_join(member):
#   print("asdsddad")
#   await member.send("Hello!")


@bot.command(pass_context=True)
async def ping(ctx):
    ''' @pong! '''
    await ctx.send('{0} Pong!'.format(ctx.author.mention))

@bot.command(pass_context=True)
async def joke(ctx):
    ''' Tells a random programmer joke '''
    await ctx.send('{0} {1}'.format(ctx.author.mention, pyjokes.get_joke()))

@bot.command(pass_context=True)
async def get_server_id(ctx):
    ''' Get's the server's ID! '''
    await ctx.send('{0}, {1}'.format(ctx.author.mention, ctx.message.guild.id))

@bot.event
async def on_member_join(member):
    print("I made it to join!")
    await member.send('Welcome to the server!')

@bot.command(pass_context=True)
async def members(ctx):
    ''' Get members '''
    members = 0
    for m in ctx.guild.members:
        members = m.guild.member_count
    members -= bots[ctx.message.guild.id]
    await ctx.send('{0} There are '.format(ctx.author.mention)+str(members)+" members")

@bot.command(pass_context=True)
async def change_name(ctx):
    ''' Change the server name! '''
    members = 0
    for m in ctx.guild.members:
        members = m.guild.member_count
    members -= bots[ctx.message.guild.id]
    await ctx.guild.edit(name = "The " + str(members) + " Dwarves")


bot.run(TOKEN)

Code

Logged in as
Marwin
543266782601936898
------
https://discord.com/oauth2/authorize?client_id=543266782601936898&scope=bot