PHP cURL not aible to show response

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I am not able to retrieve the response of the SNOMED API. Works with my browser with the same URL.
I received no error message, just an empty response.

Tried to add these parameters without change
curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);
curl_setopt($ch, CURLOPT_HTTPHEADER, array( ‘Content-Type: application/json’));
curl_setopt($ch, CURLOPT_HTTPHEADER, array( ‘Content-Type: application/x-www-form-urlencoded’));
curl_setopt($ch, CURLOPT_FOLLOWLOCATION, true);