Comment displays dosen't show default user image

I tested this module with 2 users when i style my layout.

user 1 = admin user ( with my personal picture uploded )
user 2 = authenticated user ( with the default image for all users -- User management › User settings ›)

When i copy the cd-comments.tpl.php in my theme folder, the default picture of users 2 disapear. I removed cd-comments.tpl.php and the user 2 picture was printed , i copy again the cd-comments and the picture of user 2 is gone. User 1 picture is printed with both, user 2 is not printed when i copy cd-comments.tpl.php. Same thing for ud.

Thank you