Soft switch access to LDAP

Dear All,
we are having feature trail for a customer, were our NSN soft switch shall access LDAP server installed on REDHAT 4 LINUX.

first the connectivty from the switch to ldap is ok,
using some SIP clients, we need to register to the ldap and the proceed with calls, but till now we are sending sip:register and we end up with 500 internal server error.

i started slapd debug utility and i can see candidate entry equal to 1, that means the server is able to allocate the sip uri entry sent in the regsiter but it ends up with 500 error.

please advice how to trouble shoot this issue, i can provide slapd output for your reference , and if you need other configuration data such as *.schema or ldap.config let me know.

how to upload an attachement?

best regards
hani