Can't make CB send confirmation emails

Hi, I installed CB 1.7 and only tested it after installation. It worked correctly.
However, for some time now (i can't exactly specify when it started happening) CB is not sending (or re-sending) confirmation emails.
I tried changing the settings to allow for admin approval of the new user, when that happens CB sends emails correctly notifying the user that it has been confirmed as a new member(by an admin). But i change the settings back to require email confirmation and it still won't send the confirmation.
I believe it must be a very simple setting that is not set right, but i don't understand which one it is (I've tried just about most of them).

I would really appreciate some help in this matter.
Thank You

Using joomla 1.7 with ja_purity_ii v1.2.0 and CB v1.7:

I have a similar problem. My registration process is set up to require:
a) email validation, which is then followed by,
b) moderator approval of the user's registration.

I can't get this to work properly yet.

My (test) user can register without difficulty and does receive the User Registration Pending Approval email which asks that the user confirm his/her email via the hyperlink. That part works fine.

So does the next step of CB receiving the email confirmation and updating that it the database (as viewed in CB's User Management tab).

But after that nothing else happens.

Presumably there should have been some sort of notification sent to the moderator that this user's registration is pending approval.

If I just go in to the User Management area of CB (without knowing that there are no users there who's registration is pending approval) and manually approve them, the system does send out the Registration Approval email (or whatever it's called).

Hopefully one of the moderators will spot this and have a few minutes to help.

Seems like a fundamental issue.

I have two sites, very similar, both upgraded to CB 1.7.1
both Joomla 1.5.23

Confirmation email is working on one site:
resources.scienceworld.ca/

Not working on this one:
catalystforscience.ca/

Hoping to find a solution soon. Been watching the forum for months now on this issue.
Thanks.