:include not working

I have one model User. And i have used
acts_as_commentable_with_threading plugin.
I am firing query
@comments = Comment.find(:all,:include => :user)
it generate mysql properly.
SELECT SQL_NO_CACHE * FROM comments
SELECT SQL_NO_CACHE * FROM users WHERE (users.id IN (1,4,5)) .

But when i am using comment.user in my partial file it’s firing query
again.
I don’t know why this problem is occurring.

Anyone can help me.

Thanks.