Hello everyone!
I've been struggling to find out why we receive this error when trying to use ManagedCustomerService operations, such as fetching a Selector. The account in use can manipulate everything from inside the AdWords dashboard. The keys and token seems to be valid. This account is not the main one, but it is associated with an MCC account. Inside the dashboard, I can see the account has admin privileges.
Is there anyway to check this account permissions when communicating with the API? Is there any way to teste the API connection/call through "curl" or something else? We are using the PHP lib. 
Thank you in advance,
Ricardo