REST Call from PLSQL using apex_web_service.oauth_authenticate

Hi All

DB - 19c on OCI - Apex - ver 18

This works fine via postman, but when i try to run the code below I get ORA-20001: Authentication failed. I noticed Postman has an additional field 'scope'. This has only been added in ver 19 of apex. Not sure if I need this.

 apex_web_service.oauth_authenticate(

  p_client_id      => l_clientid,

  p_client_secret    => l_client_secret,

  p_token_url      => l_token_url,

  p_wallet_path     => l_wallet_path,

  p_wallet_pwd      => l_wallet_pw,

  p_https_host      => l_token_https_host  );

Any ideas ?

tks R