Redmine

I'm trying to configure LDAP in Redmine 2.3. We have a Redmine server already, but we're migrating machines and wanted to update in the process. The server Redmine is running on is also our LDAP host. When logged in as the Redmine user, running this command is successful and displays all of the users in the system.

ldapsearch -H ldaps://10.31.14.112 -b "dc=company,dc=com" -x -D "cn=admin,dc=company,dc=com" -W

Here is how LDAP is set up on both our Redmine servers (configurations are identical):

Hitting the test option below on the old machine returns a "Successful connection" message, but on the new Redmine server I get "Unable to connect (no connection to server)".

I don't understand why it's not working, and I'm suspecting this is a bug in redmine somehow. The old Redmine server is running version v2.1.2, while the new Redmine server is (as said before) v2.3.0. I've looked everywhere to figure out what's wrong and how I can fix it, but I can find no information anywhere.

$ RAILS_ENV=production rake about
About your application's environment
Ruby version              1.9.3 (x86_64-linux)
RubyGems version          1.8.11
Rack version              1.4
Rails version             3.2.13
Active Record version     3.2.13
Action Pack version       3.2.13
Active Resource version   3.2.13
Action Mailer version     3.2.13
Active Support version    3.2.13
Middleware                Rack::Cache, ActionDispatch::Static, Rack::Lock, #<ActiveSupport::Cache::Strategy::LocalCache::Middleware:0x00000003a74c40>, Rack::Runtime, Rack::MethodOverride, ActionDispatch::RequestId, Rails::Rack::Logger, ActionDispatch::ShowExceptions, ActionDispatch::DebugExceptions, ActionDispatch::RemoteIp, ActionDispatch::Callbacks, ActiveRecord::ConnectionAdapters::ConnectionManagement, ActiveRecord::QueryCache, ActionDispatch::Cookies, ActionDispatch::Session::CookieStore, ActionDispatch::Flash, ActionDispatch::ParamsParser, ActionDispatch::Head, Rack::ConditionalGet, Rack::ETag, ActionDispatch::BestStandardsSupport, OpenIdAuthentication
Application root          /home/redmine/redmine-2.3
Environment               production
Database adapter          mysql2
Database schema version   20130217094251