[Koha] Koha API - Authentication Failure

Hi, I wanted to build an app that uses the koha API, and so i was testing it out, but I keep getting "Authentication Failure" error whichever end point I try to access. The steps i did are 1. Got the client_id / secret from koha 2. Sent a POST request to api/v1/oauth/token with required parameters and got an "access_token" returned 3. Added the token to my authorization header with header-prefix "Bearer" 4. Sent a GET request to different end points, but getting the same 401 Unauthorized error code with error : Authentication failure However if i access one of the public end points like /api/v1/biblios/{biblio_id} i can get a response If anyone has any idea why this is happening, please let me know. Thanks in advance, Aswin