Make sure that you're on at least Version 1.10+ of Minecraft! I had this exact problem as well because it normally tells you if your client is out of date to the server and it doesn't with PokeFind. I would suggest to just installing 1.11.2.
You can try these methods to join the server: 1) Use "Direct Connect" option in the server list. 2) Use a 1.10+ Version of Minecraft. 3) Use Optifine. If you still cannot connect to the server, try looking at your internet service or your firewall if it is preventing Minecraft to send out signals