fix bug

apps/exams/Lib/Action/AdminPaperAction.class.php

@@ -327,7 +327,7 @@ class AdminPaperAction extends AdministratorAction
         }
         $paper_id = intval($_GET['paper_id']);
        $b = M('exams_paper')->where(['exams_paper_id' => $paper_id])->save([
-            'attache' => 104
+            'attache' => '104'
         ]);
        var_dump($b);
         $paper    = $this->mod->getPaperById($paper_id);