[M4D]

as CNMike said TEAM_AT isn't variable...
try this (*if this defines are your teams):

pawn Код:

public OnPlayerTakeDamage(playerid, issuerid, Float:amount, weaponid)
{
    new Float:HP;
    GetPlayerHealth(playerid, HP);
    if(GetPlayerTeam(playerid) == 1)
    {
        SetPlayerHealth(playerid, HP-0);
    }
    if(GetPlayerTeam(playerid) == 2)
    {
        SetPlayerHealth(playerid, HP-0);
    }
    return 1;
}