Welcome to TG. I suspect you are being kicked by a script that makes room on the server for a supporting member. Our script kicks the non supporting member on the server that has been playing the longest continuous amount of time when a supporting member is trying to connect. Just keep trying to reconnect or if you really like the server, you can become a supporting member.
http://www.tacticalgamer.com/payments.php

From our faq:

4: Why was I kicked or banned?


There are a few innocuous reasons you may have been kicked / banned:

1. To make room for a Supporting Member. Supporting Members are entitled to reserved slots on all of our servers and we kick the longest playing Non-Supporting Member to make room for them.
2. You forgot to join a squad. Playing as a team is mandatory on TG servers. We don't allow lone wolves.
3. There is a bug when switching teams at the end of the round where you are still in the same squad as last round, but unable to leave it. Unfortunately, the game registers you as being squadless, so you can get picked up by the squadless kick. The only way to correct this is to disconnect from the server and rejoin. Sorry, we don't have any control over this.
4. Immediately upon loading into the server. This is also part of the SM Reserved Slot script. See below for how it works.
5. 4 people punished you for teamkills in a round. The ban only lasts one round and is automatic. Please jump on TeamSpeak to let us know. Also, punishing accidental teamkills can get the punishing player kicked, so please report any player who punishes accidental teamkills.


If the above don't apply and breaking one of our rules got you banned, do not start a thread in the forums. Start a thread only in the Contact an Admin forum and tell them your in-game name plus clan tag you were using at the time.