diff --git a/application/controllers/mockup/fo/walk_in_registration_stemcell/Px.php b/application/controllers/mockup/fo/walk_in_registration_stemcell/Px.php
index daf347a..04c46dd 100644
--- a/application/controllers/mockup/fo/walk_in_registration_stemcell/Px.php
+++ b/application/controllers/mockup/fo/walk_in_registration_stemcell/Px.php
@@ -585,13 +585,14 @@ class Px extends MY_Controller
 
       $ids_str = implode(',', array_unique($test_ids));
       $sql = "SELECT T_TestID, T_TestNat_GroupID FROM t_test WHERE T_TestID IN ($ids_str)";
-      $query = $this->db_smartone->query($sql);
 
       $nat_group_map = [];
-      if ($query) {
-         foreach ($query->result_array() as $r) {
+      $result = mysqli_query($this->db_smartone->conn_id, $sql);
+      if ($result) {
+         while ($r = mysqli_fetch_assoc($result)) {
             $nat_group_map[(int)$r['T_TestID']] = (int)$r['T_TestNat_GroupID'];
          }
+         mysqli_free_result($result);
       }
 
       $filtered = [];