Do you get the same error if you switch the Connection Type to Basic and supply all the information?
Are you sure your firewall is open? Can you connect with SQL*Plus?
Connection timeouts are usually caused by a firewall between client and server. Most other connection problems produce a different message.
Try deconstrucing the connection to its host, port and sid (or service) components.
Can you ping the host? ping <hostname>
Can you telnet to the host on the listener port telnet <hostname> <port number>
Can you tnsping the tns alias? tnsping E1LOCAL
If you are on windows, and the database is on the same host, check windows firewalll.