Empty data using curl and php

i have an API key. I try to retrieve JSON data like this :

<?php $access_key = "xxxxxxxxx"; $url = 'https://api.nomics.com/v1/prices?key='.$access_key; echo $url."
"; $ch = curl_init($url); curl_setopt($ch, CURLOPT_RETURNTRANSFER, true); // Store the data: $json = curl_exec($ch); curl_close($ch); // Decode JSON response: $response = json_decode($json, true); print_r($response); ?>

and i get nothing… if i try directly with the url on my browser, i receive the json answer… Maybe my curl needs to wait for answer or something like this ?

Any help please ?