The POST don't need the /add

app/Api.php

@@ -78,7 +78,7 @@ class Api {
             "comment"=>$comment,
             "feedback_category"=>$feedback_category
         );
-        $json = Api::post("campaigns/" . CAMPAIGN_ID . "/feedbacks/add", $data);
+        $json = Api::post("campaigns/" . CAMPAIGN_ID . "/feedbacks", $data);
         return json_decode($json, true);
     }