[B-Matt]

Use this simple code:

Код:

public OnPlayerTakeDamage(playerid, issuerid, Float: amount, weaponid)
{
    new Float:HP;
    GetPlayerHealth(playerid, HP);
    if(weaponid == 31) SetPlayerHealth(playerid, HP-30);
    return 1;
}

More about simple damage system look here - https://sampforum.blast.hk/showthread.php?tid=330005
I use this and it's works.