Basically because the new update of Arma 2 Operation Arrowhead has either removed or broken the feature. Not really much else to it.

******THIS WILL NOT WORK FOR EVERYONE ON EVERY SERVER AND ALTHOUGH UNLIKELY IT COULD BREAK YOUR GAME AND REQUIRE YOU TO REDOWNLOAD******

Step 1. Change your Arma 2 Operation Arrowhead to "Legacy Operations"

To do this, right click on your Arma 2 OA in your steam library and chose "Properties"

Navigate to the "Betas" tab and in the drop down section, select "Legacy"

Let the game download the legacy edition.


For some people, this is the only fix required. If you can join your server with this change and it doesn't give you and error, ignore the rest. If you still cant join for other reasons, Keep reading.



Step 2. "Battleye Initialization Failed"

This is incredibly easy to fix.

Navigate to your steam directory. Follow the folders as follows.

Steam>
Steamapps>
Common>
Arma 2 Operation Arrowhead>
BEsetup>
Setup_BattlEyeARMA2OA.exe

Launch the setup for battleye and let it re-install.

Once it has reinstalled, it should fix this glitch.


Step 3. "Bad version, Server rejected connection"

This means that the server your are trying to connect is not running a version which allows for Legacy operations to run. There is no fix that I know of to this. You will just have to find a new server ;c.


I hope this helps. If it doesn't then I'm sorry. If you want to change back, just change Arma 2 OA from "Legacy" back to the "No Beta" setting. Re install battleye if neccesery.