Reg Adding New Attributes

Hi All, I have installed OpenLdap and PHPLdapAdmin.

I have added a user which objectclass is :

objectClass inetOrgPerson posixAccount shadowAccount

I need to add a new attribute which will be application specific (application which will need LDAP authentication and based on the attribute value, it will provide service to the user).

When I tried to do the same by adding attribute and value to ldif files and then adding the ldif file, it showed error:

ldap_add: Undefined attribute type (17) additional info: AppAttribute1: attribute type undefined.

Do I need to modify related schema for the same?

Please suggest some suitable way to do the same. Is there any way that I can do it from the PhpLDAPAdmin GUI?

Thanks in advance.

-Asimananda