如何上传图片到facebook广告api?错误→图像大小调整失败:getimagesize函数返回false

我有麻烦上载图片到facebook广告api。图片位于服务器上，我正试图使用curl让它工作。我的代码如下所示，但它不起作用。知道为什么吗?由于

$targeting=array('countries'=>array('US'),'gender'=>array('1'));
$creative=array('title'=>'test me','body'=>'this is a test','link_url'=>'http://www.myurl.com','image_file'=>'test.jpg');
$adgroup_spec=array('campaign_id'=>$campaignid,
                    'name'=>'test',
                    'bid_type'=>1,
                    'max_bid'=>10,
                    'targeting'=>$targeting,
                    'creative'=>$creative
                    );
$adgroup_spec=urlencode(json_encode($adgroup_spec));
$path_to_image='@.'test.jpg';
$url="https://api.facebook.com/method/ads.createAdgroups?account_id=$MYACCOUNTID&adgroup_specs=$adgroup_spec&access_token=$accesstoken&$image_file=$path_to_image&format=json";
$ch = curl_init($url);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);
curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, false);
$output = curl_exec($ch);
curl_close($ch);

图像从未创建，我得到错误->图像调整失败:getimagesize函数返回false