su asks for password even the user is in the trusted group

feyd@fujiwara-no-sai:/etc/pam.d> groups
users wheel dialout video
feyd@fujiwara-no-sai:/etc/pam.d> cat su
#%PAM-1.0
auth     sufficient     pam_wheel.so trust group=wheel
auth     sufficient     pam_rootok.so
auth     include        common-auth
account  include        common-account
password include        common-password
session  include        common-session
session  optional       pam_xauth.so
feyd@fujiwara-no-sai:/etc/pam.d> su -
Password: