Segmentation fault in su

Hi,
  If i login as an ordinary user(admin), and try to switch to ROOT user, =
iam getting Segmentating fault, though iam member of  wheel group and =
given trust in /etc/pam.d/su=20

  %PAM-1.0 ### /etc/pam.d/su -->
   auth       required     /lib/security/pam_wheel.so group=3Dwheel

##### /etc/group -->
wheel:x:10:root,admin

I am using Redhat Linux- 7.2 in my servers. Kindly provide me a =
solution, as soon as possible.


Regards
Ahamed.MLA
Beacon Operations 24/7=20
Sify Ltd.
Chennai 
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