Thanks for your help!

My problem was Amazon EC2:
support.asternic.biz/index.php?/Knowledgebase/Article/View/17/2/revokeregister-scripts-for-amazon-ec2
The server had restarted and the MAC address changed.

At the time of this post, the scripts say chkconfig -add; it should be --add, otherwise the scripts work. Make sure the network adapter it's bound to is eth0 (it probably is unless otherwise specified in /etc/sysconfig/fop2), and if it's not the bound adapter, that file will tell you which one to specify with -i in your fop2_server commands.

Okay, so I reinstalled 2.27, and it actually shows as registered at the bottom of the page:

FOP2 - Version 2.27 - Licensed to CiviCom - Copyright © 2009-2013 Nicolás Gudiño

But here's the output of test (on v2.27):

[root@pbxserver fop2]# ./fop2_server -t
Flash Operator Panel 2 - Invalid license for this machine.
unable to initialize libusb: -99
Flash Operator Panel 2 - Valid License (1)

Connection to manager OK!

I tried to just 'make' 2.28 to upgrade, but it then goes back to demo mode.

What can we do to quickly and easily resolve this?

I keep getting 502/504 errors connecting to your site...something might be going on with your host (I have tried from multiple ISPs over several days, and this is the only part working; the rest I need to load from cache...maybe that's part of the issue with the license (can't contact servers)?

I downloaded the tgz and ungzipped it to /usr/src
then cd fop2 & make & make install
now it's saying I'm on a lite license and this is what it looks like when I register:

License Activation
------------------
Enter your serial code: notpostingthisonlinelol
Serial code not available for version 2.28.
You can register only version 2.27.

I sent several e-mails for support and got no reply...

When I attempted to upgrade from v2.27 purchased in May 2014 to v2.28, I got an error saying the license was not valid. What do I need to do in order to resolve this?