PrintBeat API - 406 Not Acceptable response

Hi, I’m trying to use the “Print Beat data access” API for an HP Latex Machine.

We’ve tested different types of connections for the API but the response is Always the same.

We have tried using different API Calls, but none of them work.

I have read the Documentation and i have used the official testing tool (https://developers.hp.com/print-beat-api-test) with no result, I have also tried making a request with postman using the github sample repository but the response is always the same.

I made sure i inserted the right key, secret, and serial number, but this is the response i keep getting when i try the "Get list of devices real time data": 

{ "data": { "smsError": { "statusCode": 406, "message": "failed to match AAA serials", "moreInfoUrl": "", "developerInfo": "", "subCode": 0, "serviceName": "Printbeat" } }, "unitSystem": "Metric" } 

Thanks in advance for you help.