zimbra edition: 509 opensource. os: redhat as 5

I built two servers as multi-server environment. Server1 is master-ldap , server2 is replication-ldap . At first , everything is ok , but after i changed the mailmode to both , when i access the webmail by https://ip , looks like everything is good , but when i click any buttom , it shows to me "code:empty_response method: searchrequest".

I still no found any log .

some suggestion ?