Using a trigger to spawn zombies in a certain area, they spawn on the roof

[insertcoins]

So, here's the deal.

 

I use a trigger to spawn zombies in a certain area as a challenge (a little maze with a prize at the end) but for some reason the zombies I spawn with the trigger all spawn on the roof. Any way to have them spawn on the ground?

 

The trigger I use:

_zombletypes = ["zZombie_Base", "z_worker3", "z_worker2", "z_worker1", "z_villager1", "z_villager2", "z_villager3", "z_worker3", "z_worker2", 
"z_worker1", "z_villager1", "z_villager2", "z_villager3", "z_worker3", "z_worker2", "z_worker1", "z_villager1", "z_villager2", "z_villager3"];
_zomblesposition =     [9615.84,11370.1,0];
_i = 1;
    for "_i" from 1 to 30 do
    {
        _genzombles = _zombletypes call BIS_fnc_selectRandom;
        _agent = createAgent [_genzombles, _zomblesposition, [], 40, "NONE"];
        _zombleselectedpos = getPosATL _agent;
        [_zombleselectedpos,_agent] execFSM "\z\AddOns\dayz_code\system\zombie_agent.fsm";
    };

[insertcoins]

bumping it

[Achmed]

Could always try setting the hight to -1 and see how they spawn then