I have moved your post to the Web Wiz Forums support forums as you posted in the wrong forum.
Depending on the settings within the Email Settings page within the admin area depends on how email notifications are sent.
By default a subscriber only receives an email for the first reply within a topic, they will not receive a notification again till they return to the forum.
The email will state that there has been a reply in the topic they are watching and there maybe more.
This helps prevent the website getting blacklisted by people who no-longer want to be part of your forum still receiving notifications and reporting them as spam.
You can change this in the Email Settings in the forums admin area so they subscribers get notifications of all replies regardless of if they have visited the forum again or not. On busy forums this does tend to lead to lots of spam complaints from past members who still get notifications and have not unsubscribed themselves, so should be set with caution.