Oracle Sql Developer: Failure - Test Failed: the Network Adapter Could Not Establish the Connection?

Problem

Please note that I changed details for security purposes. However, the problem remains intact.

I installed an Oracle 11g database on a server at location, say, herp-devDV.derp.edu. Now I have another Oracle 11g database on a server at location, say, derp-db.derp.edu.

I entered the connection name, username, password, hostname, and service name in Oracle SQL developer for both herp-devDV.derp.edu and derp-db.derp.edu. I can connect to schema in derp-db.derp.edu, but not herp-devDV.derp.edu. It gives me this message:

Failure - Test failed: The Network Adapter could not establish the connection

Details

I have the following information:

• Port 1521 is not open for either server when I telnet
• My listener is up and running for both.
• I can access derp-db.derp.edu on Oracle SQL Developer.
• Oracle client is on my local machine + Oracle SQL Developer
• I can remote desktop to both servers