Upload pano image with heading and gps using street View Publish API won't work

I'm trying to upload spherical images on street view using Publish Api. Upload of image data and place association works well, but whenever i try to upload heading and gps position data to the image server responds "OK" but then no heading nor position were associated to the image.

Here is the php code i use for the last step of info upload, i really don't know where i am wrong.

$data['uploadReference']['uploadUrl']=$upload_url;
$data['pose']['heading']=$heading_north;      
$data['pose']['latLngPair']=$latLngPair;    
$data['captureTime']['seconds']=time();    
$data['places']['placeId']=$placeid; 

$data_string = json_encode($data); 


$ch = curl_init('https://streetviewpublish.googleapis.com/v1/photo?key='.$_GOOGLE_API['api_key']);

curl_setopt($ch, CURLOPT_CUSTOMREQUEST, "POST");                             
curl_setopt($ch, CURLOPT_POSTFIELDS, $data_string);     
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);  
curl_setopt($ch, CURLOPT_HTTPHEADER, array(                                     
  'authorization: Bearer '.$_GOOGLE_API['access_token'],
  'Content-Type: application/json',                                             
  'Content-Length: ' . strlen($data_string))                                     
);                                                                                                                   
$result = curl_exec($ch);

curl_close ($ch);

EDIT:

I've implemented the second step as suggested but nothing changes.. Curl response still doesn't contains any error..

$ch = curl_init('https://streetviewpublish.googleapis.com/v1/photo/'.$photo_id.'?key='.$_GOOGLE_API['api_key'].'&updateMask=pose.heading');                                                                      
curl_setopt($ch, CURLOPT_CUSTOMREQUEST, "PUT");                                                                     
curl_setopt($ch, CURLOPT_POSTFIELDS, $data_string);  
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);                                                                      
curl_setopt($ch, CURLOPT_HTTPHEADER, array(                                                                          
        'authorization: Bearer '.$_GOOGLE_API['access_token'],
        'Content-Type: application/json',                                                                                
        'Content-Length: ' . strlen($data_string))                                                                       
    );                                                                                                                                                                                                                                   
$json_response=curl_exec($ch);
curl_close ($ch);
echo $json_response;

EDIT2: this procedure works but google apis are slow and edited data will show up in minutes..

EDIT3 (SOLVED): GET photos (list) has some chache issue. to get the correct value just updated you need to request GET photo (single) to force an effective cache update.

Try to set the values in a second step with photo.update. Don't forget to set the updateMask for the values.