C:\Documents and Settings\Wallace\Desktop\Servidor de Samp\gamemodes\Life.pwn(21531) : warning 235: public function lacks forward declaration (symbol "OnPlayerTakeDamage")

public OnPlayerTakeDamage(playerid, issuerid, Float: amount, weaponid)
{
    if(issuerid != INVALID_PLAYER_ID)
    {
        new string[128], victim[MAX_PLAYER_NAME], attacker[MAX_PLAYER_NAME];
        new weaponname[24];
        GetPlayerName(playerid, victim, sizeof (victim));
        GetPlayerName(issuerid, attacker, sizeof (attacker));
 
        GetWeaponName(weaponid, weaponname, sizeof (weaponname));
        format(string, sizeof(string), "%s has made %.0f damage to %s, weapon: %s", attacker, amount, victim, weaponname);
        SendClientMessageToAll(0xFFFFFFFF, string);
    }
    return 1;
}