I have to guess, because you have not answered the previous questions.
It appears that your query, more specifically your join is flawed. If you look at your error log, you may see that index 'class' does not exist. If you do, simple fix, add the proper join
Code:
LEFT JOIN users ON torrents.owner = users.id
and be sure that you select the class in the query.
But without more information, I am only guessing.