Why does this “The caller does not have permission” error occur?

I need to call google scipt via api, so I did the following

• I created an application for Oauth

• Created gs script, saved

• Deployed as executable api

My php code

$client = new \Google_Client(); $client->setAccessToken($_SESSION['access_token']); $service = new \Google_Service_Script($client); $request = new \Google_Service_Script_ExecutionRequest(); $request->setFunction('myFunction'); $response = $service->scripts->run('idScript', $request); 

And in the end I got this error.

  Fatal error: Uncaught Google_Service_Exception: { "error": { "code": 403, "message": "The caller does not have permission", "errors": [ { "message": "The caller does not have permission", "domain": "global", "reason": "forbidden" } ], "status": "PERMISSION_DENIED" } }