bugzilla notification problem.

Hi,

I am new to bugzilla.

In my site I am maintaining one centralized bugzilla server. I
configured nearly 10 componets.

Here the problem is,one of the componets notification is not working.
when a user  assigned a bug, the notification mail is not going to the
concerned persons.
Remaining all other component groups notifications is working fine.

Can you please help me out of this trouble telling me where should I
check and
change and do the settings and I need it as early as posiible.

Regards
Kris