joomla registration error

Hi

I am using Joomla 1.5.26 , Joomdle .82 and moodle 2.x

when I register new user , I get following error twice
Login denied! Your account has either been blocked or you have not activated it yet. Did you not get an activation e-mail and follow the validation link?

however , the actionvation link goes fine , when clicked on activation link , againt it gives an error that you are not authorized to this but also gives message that user is activated now

I see users are also created in Joomla, Moddle and Joomdle and I am can login fine

So whats the purpose of this error and how can I avoid it because it gives wrong impression to user

Looks like a joomla error. Do a quick google search and you will find a few possibilites:
1) joomla requires activiation. Is this configured in Joomla (not Joomdle) for authentication?
2) Are you using any other plugins such as jfusion. This has been known to have some conflicts.
3) Do you have any redirection plug ins,etc.