LDAP plugin error

I'm using BitNami Stack so i'll post this issue also there.

After i'll restart all services (Redmine, Apache, MySql) i can't log in via LDAP authentication. When i'll log in as local administrator and try to test connection to LDAP in Administration tab, I've got LDAP error (cannot' connect to server). After restarting redmine and mySQL few times, everything dissapears.

Any idea how to deal with this?