diff --git a/components/ILIAS/Scorm2004/classes/adlparser/SeqTreeBuilder.php b/components/ILIAS/Scorm2004/classes/adlparser/SeqTreeBuilder.php
index bec008ab203e..b8b485341c20 100755
--- a/components/ILIAS/Scorm2004/classes/adlparser/SeqTreeBuilder.php
+++ b/components/ILIAS/Scorm2004/classes/adlparser/SeqTreeBuilder.php
@@ -46,6 +46,23 @@
     DAMAGES.
 */
 
+require_once("SeqActivity.php");
+ 
+require_once("SeqRule.php");
+require_once("SeqRuleset.php");
+ 
+require_once("SeqCondition.php");
+require_once("SeqConditionSet.php");
+ 
+require_once("SeqObjective.php");
+require_once("SeqObjectiveMap.php");
+ 
+require_once("SeqRollupRule.php");
+require_once("SeqRollupRuleset.php");
+ 
+require_once("ADLAuxiliaryResource.php");
+
+
 class SeqTreeBuilder
 {
     public function buildNodeSeqTree(string $file): array