Index: branches/feature-module-update/data/class/SC_CampaignSession.php
===================================================================
--- branches/feature-module-update/data/class/SC_CampaignSession.php	(revision 15355)
+++ branches/feature-module-update/data/class/SC_CampaignSession.php	(revision 15370)
@@ -51,5 +51,6 @@
     /* キャンペーンディレクトリ名を取得 */
     function getCampaignDir() {
-        return $_SESSION[$this->key][$this->campaign_dir];
+        return isset($_SESSION[$this->key][$this->campaign_dir])
+                ? $_SESSION[$this->key][$this->campaign_dir] : "";
     }