After receiving the OAuth2.0 token successfully, we are having trouble reading from a specific customer's NetSuite environment (other environments work fine).

We are trying to read a resource like:

/services/rest/record/v1/classification?limit=10&offset=0

or

/services/rest/record/v1/inentoryItem?limit=10&offset=0

We are receiving the response:

{"type":"https://www.w3.org/Protocols/rfc2616/rfc2616-sec10.html#sec10.4.2","title":"Unauthorized","status":401,"o:errorDetails":[{"detail":"Invalid login attempt. For more details, see the Login Audit Trail in the NetSuite UI at Setup > Users/Roles > User Management > View Login Audit Trail.","o:errorCode":"INVALID_LOGIN"}]}

Is this some kind of permissions problem for the login/role we are using? We didn't see anything exciting in the Login Audit Trail except for the fact that login was denied.