diff --git a/www-api/app/Models/ResultFormatter.php b/www-api/app/Models/ResultFormatter.php
index b4821276..5eecdc3a 100644
--- a/www-api/app/Models/ResultFormatter.php
+++ b/www-api/app/Models/ResultFormatter.php
@@ -331,7 +331,7 @@ class ResultFormatter extends Model
                     "total_record" => ($total - 1),
                     "internal_return" => $out["internal_return"],
                     "result_list" => array(),
-                    "categories" => dummyCategory(),
+                    "categories" =>  $this->dummyCategory(),
                 );
                 for ($i = 0; $i < $total; $i++) {
                     $key = sprintf("%05d", $i);