Write in Your console
meta list
and look what is the version number of podbot mm. Mae sure it's R2B46d. If You don't have it yet, take it from
here.
BTW - You have the dedicated server (You can't play from that PC) or listenserver (You are creating the game and You can play on it and the people can join to Your PC)?
If You have a dedicated server You can't write just from any client console
pb bot_command, You need to use remote console. First You need to write in Your client console
rcon_password "here_your_password_to_ds"
then
rcon pb addbot 100
or other pb commands.