Brand new to Marketo REST API and I'm having trouble calling the identity service. I've followed the steps in the documentation, created a role for my API user and assigned a user to that role. Created a new custom service and copied the client_id and client_secret from the view details. I've copied the identity service URL and added /oauth/token to the end. I've checked and double-checked the values in my URL and they match what the admin site says. No matter what I try, I continually get a 401 error and the json output:
"error_description": "No client with requested id: xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx"
(where the xxxxx's are replacing the actualy client_id I passed, of course).
I can successfully get a token through the UI and I am able to use cUrl to bulk upload a file of attendees, so I think my account is set up correctly.
How can I debug this issue?