Group discussion => not displaying all the comments!

hi everyone,

on my elgg sit 1.1, not all the comments are displayed in one discussion! It stops apparently at 55!

Anyone can help me? I di not change anything in the code.

(url: http://etudiants.sciencespoaix.com)

http://etudiants.sciencespoaix.com/mod/groups/topicposts.php?topic=178&group_guid=18