OAuth 2.0 Client Credentials grant type . Getting 401 error "Couldn't authenticate you"

I have setup a oAuth client using admin center and selected the kind as confidential.

Thereafter i am creating a access token using following endpoint. When i use the token with Ticket API for inistance list comment, i get 401 , "Couldn't authenticate you"

I am not getting if i am missing any setup ? I have followed this guide https://support.zendesk.com/hc/en-us/articles/4408845965210-Using-OAuth-authentication-with-your-application#topic_s21_lfs_qk

Also i am interested in the client credential grant flow and not the authorization code grant flow.

https://support.zendesk.com/hc/en-us/articles/8983332483226-Announcing-support-for-OAuth-2-0-Client-Credentials-grant-type

curl https://mydomain.zendesk.com/oauth/tokens \

-H "Content-Type: application/json" \

-d '{"grant_type": "client_credentials",

"client_id": "myclient", "client_secret": "dummy",

"scope": "read" }' \

-X POST