TI-API: Python, Sandbox Backlog Order API error 401

PS C:\Davidlocal> & C:/Davidlocal/Apps/python.exe c:/Davidlocal/PMD_TI_BACKLOG/ExampleTI_2/python/TEST_BKGOrderConfirm.py
Welcome to the backlog API example script!
We will test the create and retrieve order functions using Python.
Please replace lines 233-239 with your own customer credentials.

Authentication Successful! Token: *MASKED*
Customer sold-to ID is *MASKED*.
API authentication ID is *MASKED*.
Test ID for order is *MASKED*.
WARNING: Unexpected HTTP status code 401.

{
    "error": "invalid_client",
    "error_description": "client_id or client_secret are not correct",
    "error_uri": "See the full API docs at https://api-portal.ti.com/order-api-authentication"
}

Create Order: FAIL (90 ms).
Supplier order # is MISSING.
Test procedure will terminate now.

import json
import os
from datetime import datetime
from TI_Backlog_API_V2 import TI_Backlog_Orders
import textwrap
import requests


class Backlog_Example_Script():

    def __init__(self, server, clientID, clientSecret, shipTo, soldTo, debug=True):

        self.server = server
        self.clientID = clientID
        self.clientSecret = clientSecret
        self.shipTo = shipTo
        self.soldTo = soldTo
        self.debug = debug
        self.access_token = self.retrieve_access_token()

    def retrieve_access_token(self):
        # Define your API credentials and server URL
        clientID = self.clientID
        clientSecret = self.clientSecret
        server = self.server

        auth_endpoint = f"{server}/v2/oauth/token"

        auth_payload = {
            "grant_type": "client_credentials",
            "client_id": clientID,
            "client_secret": clientSecret
        }

        try:
            response = requests.post(auth_endpoint, data=auth_payload)
            response.raise_for_status()
            access_token = response.json().get("access_token")

            if access_token:
                print("Authentication Successful! Token: {}".format(access_token))
                return access_token
            else:
                print("Authentication Failed. No access token received.")
                print("Response Content:", response.content.decode())
                exit(1)

        except requests.exceptions.RequestException as e:
            print(f"Authentication Error: {e}")
            exit(1)

        except Exception as e:
            print(f"An error occurred: {e}")
            exit(1)

    def execute(self):
        self.now = datetime.now()
        self.testID = self.now.strftime("TEST%Y%m%d%H%M%S")
        print("Customer sold-to ID is {}.".format(self.soldTo))
        print("API authentication ID is {}.".format(self.clientID))
        print("Test ID for order is {}.".format(self.testID))

        steps = [
            self.__create_order,
            self.__retrieve_order,
        ]

        for step in steps:
            failure = step()

            if failure:
                print("Test procedure will terminate now.")
                exit(1)

        print("Test procedure completed successfully.")

    def __create_order(self):
        self.ordersAPI = TI_Backlog_Orders(
            server=self.server,
            client_id=self.clientID,
            client_secret=self.clientSecret,
        )

        self.ordersAPI.add_item_to_cart(
            part_number='SN7407N',
            quantity=10000,
            delivery_date=datetime(year=2027, month=6, day=15),
            unit_price=0.30,
            currency_code='USD'
        )

        response = self.ordersAPI.post_order(
            customer_name='Test Customer',
            customer_order_number=self.testID,
            ship_to=self.shipTo
        )
        outcome = self.get_result(response=response)

        print("Create Order: {} ({} ms).".format(
            outcome,
            int(response.elapsed.total_seconds() * 1000)
        ))

        self.supplierOrderID = "MISSING"
        if outcome == "PASS":
            self.supplierOrderID = response.json()['orders'][0]['orderNumber']
        print("Supplier order # is {}.".format(self.supplierOrderID))

        return outcome == "FAIL"

    def __retrieve_order(self):
        response = self.ordersAPI.retrieve_order_by_customer_number(
            customerOrderNumber=self.testID
        )
        outcome = self.get_result(response=response)

        print("Retrieve Order: {} ({} ms).".format(
            outcome,
            int(response.elapsed.total_seconds() * 1000)
        ))

        return outcome == "FAIL"

    def get_result(self, response, code=200):
        result = 'PASS' if response.status_code == code else 'FAIL'

        if self.debug:
            print(response.text)

        return result

print("Welcome to the backlog API example script!")
print("We will test the create and retrieve order functions using Python.")
print("Please replace lines 233-239 with your own customer credentials.\n")

backlog_example = Backlog_Example_Script(
    server='https://transact-pre.ti.com/v1/oauth/accesstoken',
    clientID='*MASKED*',
    clientSecret='*MASKED*',
    shipTo='*MASKED*',
    soldTo='*MASKED*',
    debug=True
)

backlog_example.execute()