Facebook Ads API Invalid Parameter issue

I'm trying to create an ad using the Facebook Ads API. So, far I've already created the Ad Set, Ad Creative and Campaign but, when I use the following code to create an ad group, I'm receiving Invalid Parameter exception. Please suggest me if I've any error in the following code.

$campaignId = "xxx";
$appId= "xx";
$ci = "xxx";
$accountId = "xxx";
$appSecret= "xxx";
$accessToken= "xxx";

Api::init($appId, $appSecret, $accessToken);
$api = Api::instance();

$adgroup = new AdGroup(null, $accountId);
$adgroup->setData(array(
  AdGroupFields::CREATIVE => 
    array('creative_id' => $ci),
  AdGroupFields::NAME => 'My First AdGroup',
  AdGroupFields::CAMPAIGN_ID => $campaignId,
  AdGroupFields::ADGROUP_STATUS => AdGroup::STATUS_PAUSED,
));

$adgroup->create();

The error I receive:

Fatal error: Uncaught exception 'FacebookAds\Http\Exception\AuthorizationException' with message 'Invalid parameter' in /var/www/fb/vendor/facebook/php-ads-sdk/src/FacebookAds/Http/Exception/RequestException.php:137 Stack trace: #0 /var/www/fb/vendor/facebook/php-ads-sdk/src/FacebookAds/Http/Client.php(216): FacebookAds\Http\Exception\RequestException::create(Array, 500) #1 /var/www/fb/vendor/facebook/php-ads-sdk/src/FacebookAds/Http/Request.php(282): FacebookAds\Http\Client->sendRequest(Object(FacebookAds\Http\Request)) #2 /var/www/fb/vendor/facebook/php-ads-sdk/src/FacebookAds/Api.php(152): FacebookAds\Http\Request->execute() #3 /var/www/fb/vendor/facebook/php-ads-sdk/src/FacebookAds/Api.php(194): FacebookAds\Api->executeRequest(Object(FacebookAds\Http\Request)) #4 /var/www/fb/vendor/facebook/php-ads-sdk/src/FacebookAds/Object/AbstractCrudObject.php(248): FacebookAds\Api->call('/act_1602736963...', 'POST', Array) #5 /var/www/fb/ads.php(46): FacebookAds\Object\AbstractCrudObject->create() #6 {main} thrown in /var/www/fb/vendor/facebook/php-ads-sdk/src/FacebookAds/Http/Exception/RequestException.php on line 137