UPS Rating API集成报错：返回Invalid Authentication Information

我在集成UPS Rating API时碰到了认证问题，具体信息如下：

请求URL：https://wwwcie.ups.com/api/rating/v1/Rate?additionalinfo=string

请求体：

{
    "RateRequest": {
        "shipper": {
            "address": {
                "postal_code": "12345",
                "country_code": "US"
            }
        },
        "shipTo": {
            "address": {
                "postal_code": "54321",
                "country_code": "US"
            }
        },
        "shipment": {
            "package": {
                "dimensions": {
                    "unit_of_measurement": "IN",
                    "length": "10",
                    "width": "6",
                    "height": "4"
                },
                "weight": {
                    "unit_of_measurement": "LBS",
                    "weight": "1"
                }
            }
        }
    }
}

返回错误：

{
    "response": {
        "errors": [
            {
                "code": "250002",
                "message": "无效的认证信息。"
            }
        ]
    }
}

尽管已经在请求头中传入了access-token，但始终返回上述认证无效的错误。

内容的提问来源于stack exchange，提问作者Prashanth v