Bot icon displaying as playing sound, but no sound playing out

Question

...
import atexit, shelve, asyncio, random, time, math, datetime, sys, os, pickle

from gtts import gTTS
from gtts.tts import tts_langs as tl

import discord
from discord.ext import commands
from discord_components import *

bot = commands.Bot(command_prefix="&")

@bot.command(aliases=["tp","ttsp"])
async def ttsplay(ctx, lang, *string):
    global storage
    if string:
        if lang in tl():
            t = gTTS(text=str(' '.join(string)), lang=lang)
            if os.path.isdir(f"./storage/{ctx.guild.id}"):
                t.save(f"./storage/{ctx.guild.id}/tts-result.mp3")
            else:
                os.mkdir(f"./storage/{ctx.guild.id}")
                t.save(f"./storage/{ctx.guild.id}/tts-result.mp3")
            if not ctx.voice_client:
                vc = await ctx.author.voice.channel.connect()
            elif ctx.author.voice.channel and ctx.author.voice.channel != ctx.voice_client.channel:
                await bot.voice_cilent_in(ctx.message.server).disconnect()
                vc = await ctx.author.voice.channel.connect()
            else:
                vc = ctx.guild.voice_client
            vc.play(discord.FFmpegPCMAudio(f"./storage/{ctx.guild.id}/tts-result.mp3"), after=lambda e: print(e))
            await ctx.send("done!")
        else:
            await ctx.send(embed = discord.Embed(
                title = f":warning: 지원하지 않는 언어입니다.",
                description = f"```지원 언어 목록 : {', '.join(list(tl().keys()))}```",
                colour = discord.Colour.red()))
    else:
        await ctx.send(embed = discord.Embed(
            title = ":warning: tts로 변환할 인자가 주어지지 않았습니다. ( &tts <언어> <문장> )",
            color = discord.Colour.red()
        ))

bot.run("token")

I did like this, but the bot displays as playing sound, but not sound comes out. how can i fix this? i have ffmpeg.exe, ffplay.exe, ffprobe.exe in The script's path. and, the audio is saved in the folder with name(ctx.guild.id).