php - Invalid Credentials - Google Drive API

one text

The below api call always returns invalid credentials

$ch = curl_init();
$fileId = 'myfile_id';
$key = 'apikey';
$accessToken = 'access_token'

curl_setopt($ch, CURLOPT_URL, 'https://www.googleapis.com/drive/v2/files/'.$fileId.'?key='.$key);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($ch, CURLOPT_CUSTOMREQUEST, 'GET');

curl_setopt($ch, CURLOPT_ENCODING, 'gzip, deflate');

$headers = array();
$headers[] = 'Authorization: Bearer '.$accessToken;
$headers[] = 'Accept: application/json';
curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);

$result = curl_exec($ch);
print_r($result);
if (curl_errno($ch)) {
    echo 'Error:' . curl_error($ch);
}
curl_close($ch);

Response

{ "error": { "errors": [ { "domain": "global", "reason": "authError", "message": "Invalid Credentials", "locationType": "header", "location": "Authorization" } ], "code": 401, "message": "Invalid Credentials" } } 

I am calling the api immediatly after recieivng the access token. So I am sure that it is not expired and the api key is also correct.

Do anyone have any idea about this ?