400 Bad Request when trying to post the API token request

Hello EveryOne,

When we are trying to generate the token using the post api - https://api.onesourcetax.com/oauth2/v1/token call  for the machine id and we are getting 400 Bad request. 

for the authorization we are using Basic Auth and passing the Client Key as a user id and Cleint Secret as a password and in body we pass the grant_type = 'client_credentials' and scope = 'urn:tr:onesource:auth:api:apiadministration'

so could please help to resolve the issue.

    "title": "SSGS3001: Error occurred while generating access token",
    "detail": "SSGS3001: Error occurred while generating access token",
    "error_code": "SSGS3001",
    "status": 400,
    "instance": "/oauth2/v1/token",
    "api_requestId": "rrt-0e318a235c1404da5-b-ea-917751-38391458-55",
    "correlationId": "1b304749-8646-40ab-b13a-d36325fc8844"
}