some of rcon commands aren't working for me either, like admin.listPlayers and admin.yell (i could be doing this one wrong tho)
For admin.listPlayers, try:
The format of admin.yell is:
admin.yell <message> <duration [in ms]> <players>
So for that, try something like:
admin.yell "What's going on" 40000 all
It's described as "Display a message, very visibly on playersâ€™ screens, for a certain amount of time. The duration must be more than 0 and at most 60000 ms. The message must be less than 100 characters long. "
The PDF in this .zip talks more about each command and how it's used: http://blogs.battlefield.ea.com/battlef ... c2-pc.aspx