fixed isset issue

git-svn-id: https://plugins.svn.wordpress.org/wordpress-by-circle-tree/trunk@743380 b8457f37-d9ea-0310-8a92-e5e31aec5664
version 3.0.1

git-svn-id: https://plugins.svn.wordpress.org/wordpress-by-circle-tree/trunk@743381 b8457f37-d9ea-0310-8a92-e5e31aec5664