GET IT LEGAL AND FREE
I CAN’T SEE ANY SERVERS @Apathy
This is almost invariably due to HTTP traffic to the game being blocked by a firewall or antivirus software.
In the case of firewalls, the game requires an exception (as would any multiplayer game) to be able to connect and play online.
Some anti-virus software incorrectly blocks the server-listing traffic from the game with “features” such known as HTTP filtering or “Link Scanning”
AVG Anti-Virus is particularly notorious for this, and requires re-installing AVG to fully disable the “feature”.
In rare cases this can be caused by multicore CPU timing (see “My server and/or game is jittery” below), third-party addons, or the listing server being temporarily offline.