I'm trying to invoke the List Organizations Limits REST API in my developer edition of Salesforce.  I'm getting the following error returned:

[{"message":"limits resource is not enabled","errorCode":"API_DISABLED_FOR_ORG"}]; HTTP Status: 403

The user I am logging in as has the profile System Administrator.  And the System Administrator profile has the Administrative Permission of API Enabled ticked.   I'm using the same login to successfully access the other REST API resources.

Any help is greatly appreciated.