python-无法将文件上载到AWS S3 bucket中定义的文件夹

我正在尝试从本地上传一个csv文件到awsss3 bucket。下面给出了我正在使用的代码,但没有看到将文件上载到定义的S3文件夹。有人能帮忙吗?

import boto3
from botocore.client import Config

ACCESS_KEY_ID = 'accesskeyid'
ACCESS_SECRET_KEY = 'secretkeyid'
BUCKET_NAME = 'bucketname'

data = open('/desktop/file.csv', 'rb')

s3 = boto3.resource(
's3',
aws_access_key_id=ACCESS_KEY_ID,
aws_secret_access_key=ACCESS_SECRET_KEY,
config=Config(signature_version='s3v4')
)
s3.Bucket(BUCKET_NAME).put_object(Key='/sub-folder/sub-folder2/file.csv', Body=data)

print ("Uploaded successfully")

有人能帮我找到哪里出了问题吗?谢谢