I have received a message in my in box and as I am logged in have tried to reply by clicking on the reply icon below the message next to the forward icon but I keep getting the following screen:

You are not logged in or you do not have permission to access this page. This could be due to one of several reasons:
You are not logged in. Fill in the form at the bottom of this page and try again.
You may not have sufficient privileges to access this page. Are you trying to edit someone else's post, access administrative features or some other privileged system?
If you are trying to post, the administrator may have disabled your account, or it may be awaiting activation

Below this is log in and password fields which when I complete, thanks me for logging in and then logs me in and then goes straight back to :

You are not logged in or you do not have permission to access this page. This could be due to one of several reasons:
You are not logged in. Fill in the form at the bottom of this page and try again.
You may not have sufficient privileges to access this page. Are you trying to edit someone else's post, access administrative features or some other privileged system?
If you are trying to post, the administrator may have disabled your account, or it may be awaiting activation

Not sure what I'm doing wrong........