hey hanane,
That was strange, if i switch your wanderers template to Joomla default template, the comment link is disappeared from your old group stream, but it appear on my test group and the comment link is work fine.
May i know did you have modify or overridden some of the css or core file in current wanderers template?
By the way, I've tried to connect with your FTP server, but hitting following error :
Error: Connection timed out
Error: Could not connect to server
please advise.