Error message in a link

Hello Matt... I've installed this block on differents serves (Moodle 1.9) and I allways get the same error when clicking on the link that is on the name of each group: A pop-up window with the error message 'Course module is incorrect'.

The url in the pop-up has this format:
/mod/assignment/submissions.php?id=undefined&userid=undefined&mode=single&offset=0

Is there a quick way to override this link? 
Thanks in advance for your time...