Problem: Deathmatch -> Players are immortal

[mimic-ger]

I have a Problem:
On my Deathmatch-Server it often happen, that the Players can?t kill each other.They are immortal. I don?t know why... It happen without a regularity. It isn?t triggerd by a special action or so.

The only thing that helps, is to restart the Server. Has anyone problems like this ? Or even a solution 

[Serafim]

Are you trying to do a DM server or a TDM one? Because if you set teams, you can't teamkill people. So set the team for every class as -1

[Aaron]

Lag could be causing it also.