Deny/permit lines

Hello!
In the Extesions tab there were lines deny/permit. But the deny/permit lines have disappeared. What it could be?
Help please.
Thanks!

FreePBX 2.5.1.5

[[email protected] ~]# uname -a
Linux elastix.example.com 2.6.18-92.1.22.el5 #1 SMP Tue Dec 16 12:03:43 EST 2008 i686 i686 i386 GNU/Linux

[[email protected] ~]# asterisk -v
Asterisk 1.4.25.1, Copyright © 1999 - 2008 Digium, Inc. and others.

If you click on an existing extension you will see them. They do not show up until the extension is created.