Now its ok. I contacted out ldap admin an he told me that the ldap query that calypso was sending to ldap was wrong.
I modified the ldap.searchBase to:
ou=people,dc=staff,dc=example,dc=com (added ou=people)
Now the logs are ok:
2011-02-02 11:53:27,478 [http-8080-2] DEBUG [gr.abiss.calipso.wicket.LoginPage] - Trying to obtain a user via authenticate()
2011-02-02 11:53:27,478 [http-8080-2] DEBUG [gr.abiss.calipso.acegi.LdapAuthenticationProvider] - attempting authentication via LDAP
2011-02-02 11:53:27,582 [http-8080-2] DEBUG [gr.abiss.calipso.acegi.LdapAuthenticationProvider] - Standard LDAP bind successful
2011-02-02 11:53:27,592 [http-8080-2] DEBUG [gr.abiss.calipso.acegi.LdapAuthenticationProvider] - attributes: {mail=mail:
x...@staff.example.com, cn=cn: Firstname Surname}
2011-02-02 11:53:27,592 [http-8080-2] DEBUG [gr.abiss.calipso.acegi.LdapAuthenticationProvider] - user details retrieved from LDAP, now checking local database