Hi Brian,
I have tested this plugin on Moodle 2.1 with no problems so this may be a configuration issue. If you enable debugging in Moodle you should get more information on the error in the page. Possible problems that may come up:
Current user does not have the capability to view the page (requires either "block/echo360_configuration:viewasinstructor" or "block/echo360_configuration:viewasstudent").
Incorrect EchoSystem URL (Check that you can connect directly from the Moodle server to the EchoSystem URL specified in the configuration - ie use a web browser or curl on the Moodle webserver to try and view the EchoSystem login page)
Incorrect port - the above URL should include the port number. This is the port number to access the EchoCenter (not the EchoSystem login page - that is a different port). This is port 8080 by default but can be changed.
Firewall on the EchoSystem Server, or Moodle WebServer. The Moodle Webserver needs to be able to connect to the EchoSystem Server on the specified port above, if there is a firewall in place it needs to have this port opened.
Let me know how you go with this.
Regards, Damyon Wiese