Размещение ордера на бирже Huobi с помощью API

Пытаюсь разместить ордер на бирже Huobi с помощью API, выдает ошибку:

{'status': 'error', 'err-code': 'api-signature-not-valid', 'err-msg': 'Signature not valid: Verification failure [校验失败]', 'data': None}

Вот сам код:

import requests
import json
from urllib.parse import urlencode
import hashlib
import hmac
import base64
from datetime import date, datetime, timedelta

hb_access = "5f3db95e"
hb_secret = "b1311c37"

def placeOrder(symbol, type, amount, price):
    timestamp = str(datetime.utcnow().isoformat())[0:19]
    account_id = 21711111
    data = {
        'symbol': symbol,
        'type': type,
        'amount': amount,
        'price': price
    }
    params = urlencode({'AccessKeyId': hb_access,
                        'SignatureMethod': 'HmacSHA256',
                        'SignatureVersion': '2',
                        'Timestamp': timestamp,
                        'Account-id': account_id
                        })
    method = 'POST'
    base_uri = 'api.huobi.pro'
    endpoint = '/v1/order/orders/place'
    pre_signed_text = method + '\n' + base_uri + '\n' + endpoint + '\n' + params
    hash_code = hmac.new(hb_secret.encode(), pre_signed_text.encode(), hashlib.sha256).digest()
    signature = urlencode({'Signature': base64.b64encode(hash_code).decode()})
    url = 'https://' + base_uri + endpoint + '?' + params + '&' + signature
    resp = requests.post(url, json=data)
    print(url)
    print(resp.json())

placeOrder("htusdt", "buy-limit", 1000, 0.0000000715)

Помогите, подскажите)