Artillery barrage

[GodsFist 19]

Hello. i'm making a mp mission of the Khe Sanh attack in the Vietnam war and i'm putting in a Artillery barrage.

At the beginning everythin works fine and the Barrage is working great,

but when i put in more than 20 enemies AI the barrage dissapears.

 

Here's my Artillery script that i found on the internet.

 

if (isnil "DZ_fnc_MortarFire") then {
    DZ_fnc_MortarFire = {
        private ["_ammo", "_marker", "_xcoord", "_ycoord", "_timer", "_fire"];
        _ammo = _this select 0;
        _marker = _this select 1;
        _xcoord = _this select 2;
        _ycoord = _this select 3;
        _timer = _this select 4;
        _fire = true;
        while {_fire} do {
            _firerun = _ammo createvehicle [(getmarkerpos _marker select 0) + random _xcoord, (getmarkerpos _marker select 1) + random _ycoord, getmarkerpos _marker select 2];
            sleep (random _timer);
        };
    };
};

I've placed a trigger with mf1 = ["Bo_GBU12_LGB", "mort1", 100, 150, 17] spawn DZ_fnc_MortarFire in the  in the on activation.

and a marker called mort1

 

Can someone please help me what I'm doing wrong.