Wieso crashtd er Server

Hier befhel: /kennzeichen
wenn man /kennzeichen 99999999999999999999 eingibt crasht es
dcmd_kennzeichen(playerid,params[])
{
new kz[15];
if(sscanf(params,"s", kz)) { return SendClientMessage(playerid, COLOR_GRAD1, "Benutzung: /kennzeichen [Text(Höchstens 9 Buchstaben/Zahlen)]"); }
if(strlen(kz) >= 12 && strlen(kz) <= 23)
{
return 1;
}
if(!IsPlayerInAnyVehicle(playerid)) { return SendClientMessage(playerid, COLOR_GRAD1, "Du bist in keinem Fahrzeug!"); }
//if(KennzeichenErlaubnis[playerid] == 0) { return SendClientMessage(playerid, COLOR_GRAD1, "Du hast kein Kennzeichen in der Stadthalle gekauft!"); }
if(Dtc_PlayerHaveCar[playerid][Dtc_PlayerKey[playerid]])
{
new vehiclefid = GetPlayerVehicleID(playerid);
SetVehicleNumberPlate(vehiclefid, kz);
SetVehicleToRespawn(vehiclefid);
new Float: X,Float: Y,Float: Z;
GetPlayerPos(playerid,X,Y,Z);
SetVehiclePos(vehiclefid,X,Y,Z);
PutPlayerInVehicle(playerid,vehiclefid,0);
new name[MAX_PLAYER_NAME]; //str[128];
GetPlayerName(playerid, name, sizeof name);
format(str, sizeof str, "/YGGC/Autos/%s%d.dtcar", name,Dtc_PlayerKey[playerid]);
dini_Set(str, "Plate", kz);
if(pDaten[playerid][PremiumAutos] >= 1)
{
for(new x = 0; x < MaxVeh; x++)
{
PlayerCar[playerid][x][Plate] = kz;
}
}
else
{
for(new x = 0; x < NMaxVeh; x++)
{
PlayerCar[playerid][x][Plate] = kz;
}
}
//KennzeichenErlaubnis[playerid] = 0;
}
return 1;
}

was macht die abfrage?

if(strlen(kz) >= 12 && strlen(kz) <= 23)

Wie muss ich das denn amchen das es nicht crasht