I had this problem too. For me the fix was: Add the server you want to join to your server list. Don't click on it yet. Wait until it times out. Now refresh. Now you should be able to join.
By the way: Hamachi isn't for cracked servers only. If you want to host a server, but haven't done port-forward, then Hamachi is the best solution.
By the way: Hamachi isn't for cracked servers only. If you want to host a server, but haven't done port-forward, then Hamachi is the best solution.