diff --git a/src/Elements/Bundle/AlternateObjectTreesBundle/Resources/public/js/config/panel.js b/src/Elements/Bundle/AlternateObjectTreesBundle/Resources/public/js/config/panel.js
index a8979d5..9ac8655 100644
--- a/src/Elements/Bundle/AlternateObjectTreesBundle/Resources/public/js/config/panel.js
+++ b/src/Elements/Bundle/AlternateObjectTreesBundle/Resources/public/js/config/panel.js
@@ -200,8 +200,8 @@ pimcore.plugin.alternateObjectTrees.config.panel = Class.create({
             }
 
             Ext.Ajax.request({
-                url: "/admin/elements-alternate-object-trees/admin/alternate-object-tree",
-                method: "POST"
+                url: "/admin/elements-alternate-object-trees/alternate-object-tree",
+                method: "POST",
                 params: {
                     name: value
                 },
diff --git a/src/Elements/Bundle/AlternateObjectTreesBundle/Service.php b/src/Elements/Bundle/AlternateObjectTreesBundle/Service.php
index 150dd2c..de1b73a 100644
--- a/src/Elements/Bundle/AlternateObjectTreesBundle/Service.php
+++ b/src/Elements/Bundle/AlternateObjectTreesBundle/Service.php
@@ -62,12 +62,14 @@ public function getTreeId() {
      */
     public function getLevelDefinitionByLevel($level)
     {
-        $levelDefinition = $this->levelDefinitions[$level - 1];
-        $class = $this->getClass();
-        if ($levelDefinition && $class) {
-            $levelDefinitionClass = 'Elements\\Bundle\\AlternateObjectTreesBundle\\LevelDefinition\\'.ucfirst($levelDefinition['type']);
+        if(array_key_exists($level - 1, $this->levelDefinitions)) {
+            $levelDefinition = $this->levelDefinitions[$level - 1];
+            $class = $this->getClass();
+            if ($levelDefinition && $class) {
+                $levelDefinitionClass = 'Elements\\Bundle\\AlternateObjectTreesBundle\\LevelDefinition\\' . ucfirst($levelDefinition['type']);
 
-            return new $levelDefinitionClass($class, $levelDefinition['config']);
+                return new $levelDefinitionClass($class, $levelDefinition['config']);
+            }
         }
 
         return null;