Good news is that you are not global banned if you can join other servers (if you were, you would not be able to join any Arma 2 multiplayer session). I recommend trying to contact server admins, they are pretty desperate from hacking and cheating these days, so they can ban someone by accident. I also recommend that you ensure that all stuff you carried or had in your tent was not cheated, because you can get ban only by possessing those thing, not just creating (these are actual ingame weapons: http://www.dayzwiki.com/wiki/Weapons) Btw stuff in tents are saved on server (working most of time), until someone find that tent and loot it. In the meantime just switch server and play with your friend without giving them weapons. FInding your first weapon and shooting first zombies on your own is great experience, so let them live it through.