Very weird error with tables?

I have a for loop that is supposed to spawn zombies on different locations but I encounter two errors. Number one, the zombie dies immediately after he got teleported, and number two I get this in the output Position is not a valid member of NumberValue. This output is different each time I load the game. Sometimes NumberValue, sometimes script and sometimes even camera get displayed at the end of the error output.

    local zombieSpawns = workspace:GetChildren("zombieSpawns")
    for i = 1, zombieAmount.Value do
        local Zombies = workspace:GetChildren("Zombiess")
        if  #Zombies <= zombieMax then
            local zombieClone = game:GetService("ServerStorage").Zombie:Clone()
            zombieClone.Parent = workspace.zombiess
            local randomSpawn = math.random(1, #zombieSpawns)
            zombieClone:MoveTo(zombieSpawns[randomSpawn].Position + Vector3.new(0,1,0))
        end
    end

Thanks in advance, Kryddan