Reg su -username problem

[tce tce]

Dear All,

  I am using RedHat Enterprise Linux -4.0 and just now I upgraded my system. When I enter a command su - username. It shows incorrect password. when I create a new user now also I could not switch to that user account. I searched all the solution for this issue in the net. It does not work. Kindly give me your suggestion.

  Thanks & Regards
Thamizh
   
  here is my /etc/pam.d/su file
   
  #%PAM-1.0
auth       sufficient   /lib/security/$ISA/pam_rootok.so
# Uncomment the following line to implicitly trust users in the "wheel" group.
#auth       sufficient   /lib/security/$ISA/pam_wheel.so trust use_uid
# Uncomment the following line to require a user to be in the "wheel" group.
#auth       required     /lib/security/$ISA/pam_wheel.so use_uid
auth       required     /lib/security/$ISA/pam_stack.so service=system-auth
account    required     /lib/security/$ISA/pam_stack.so service=system-auth
password   required     /lib/security/$ISA/pam_stack.so service=system-auth
# pam_selinux.so close must be first session rule
session    required     /lib/security/$ISA/pam_selinux.so close
session    required     /lib/security/$ISA/pam_stack.so service=system-auth
# pam_selinux.so open and pam_xauth must be last two session rules
session    required     /lib/security/$ISA/pam_selinux.so open multiple
session    optional     /lib/security/$ISA/pam_xauth.so
~


       
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