Twitter API Chatbot Create a new welcome message

I am referring to Twitter API > https://developer.twitter.com/en/docs/direct-messages/welcome-messages/api-reference/new-welcome-message documentation. I am passing data as below format-

Image atttach: Authorization OAuth1.0 with credential keys

Image atttach:Body section

Header as -- Content-Type:application/json API return response as >>

{
    "errors": [
        {
            "code": 32,
            "message": "Could not authenticate you."
        }
    ]
}

What could be the issue?