I did it !!!
well at last I could do it !
I'll write the steps to follow.

THIS IS HOW TO AUTHENTICATE OpenSuSE 12.2 AGAINST LDAP WITHOUT TLS/SSL :-)

1) uninstall yast2-ldap-client
2) make sure you have installed openldap2
2) install nss_ldap & pam_ldap
3) in /etc/openldap/ldap.conf add
BASE dc=example,dc=com
URI ldap://hostname
4) in /etc/ldap.conf add
host hostname
base dc=example,dc=com
ssl no
5) in /etc/nsswitch
passwd: compat ldap
group: compat ldap
6) in /etc/pam.d/common-auth add the line (I added it at the begining of the file)
auth sufficient pam_ldap.so
7) in /etc/pam.d/common-session add the line (I added it at the begining of the file)
session sufficient pam_mkhomedir.so

THAT'S ALL FOLKS !!!

Have a lot of fun...