Why my Fireball script don't work? Help me, beacouse idk what to do

rs = game:GetService("ReplicatedStorage")
ss = game:GetService("ServerStorage")
local tweenservice = game:GetService("TweenService")

rs.RemoteEvents.FireAnigilation.OnServerEvent:Connect(function(player, Mouse) 
    local char = player.Character
    local hum = char:WaitForChild("Humanoid")
    local pposX = char.UpperTorso.Position.X
    local pposY = char.UpperTorso.Position.Y
    local pposZ = char.UpperTorso.Position.Z
    print(pposX,pposY,pposZ)
    pposY = pposY + 10
    local core = rs.FireAnigilation.core:Clone()
    core.Parent = workspace
    core.Position = Vector3.new(pposX,pposY,pposZ)
    local velocity = Instance.new("BodyVelocity", core)
    velocity.MaxForce = Vector3.new(5000,5000,5000)
    velocity.Velocity = CFrame.new(core.Position, Mouse).LookVector * 100
end)

WHYYYY? When ball is small, fireball is working but when fireball is big, he doesn't work(((