My gun script is not working at all. It sends bullets flying in the wrong direction??

My gun script goal is to send a bullet flying at a target but when I play it in-game not in studio the bullets fly in the wrong direction. Can anyone fix the code of this? Thanks in advanced!

originalAmmo = script.Parent.Configure.Ammo.Value

function computeDirection(vec)
    local lenSquared = vec.magnitude^2
    local invSqrt = 1 / math.sqrt(lenSquared)
    return Vector3.new(vec.x * invSqrt, vec.y * invSqrt, vec.z * invSqrt)
end

local isActive = false
local canfire=true
local playerName

function fire(v)
    if canfire==true then
        script.Parent.Handle.Fire2:Play()
        script.Parent.Handle.Fire:Play()
        script.Parent.Configure.Ammo.Value = script.Parent.Configure.Ammo.Value - 1
        local dir = v - script.Parent["Handle"].Position
        dir = computeDirection(dir)
        local pos = script.Parent["Handle"].Position + (dir * 8)
        local p = Instance.new("Part")
        p.Shape = "Cylinder"
        p.Anchored = true
        p.Name = "Projectile"
        p.Material = "Neon"
        p.Color = Color3.new(255,255,255)
        p.BrickColor = BrickColor.new("Institutional white")
        p.Size = Vector3.new(.5, 2, .5)
        p.Orientation = dir
        p.CanCollide = false
        local s = script.Parent["ProjectileScript"]:Clone()
        s.Disabled = false
        s.Parent = p
        p.Parent = game.Workspace
        s.Value.Value = script.Parent.Configure.Damage.Value
        s.Headshot.Value = script.Parent.Configure.HeadshotDamage.Value
        p.Parent = workspace
        p.Anchored = false
        p.Position =script.Parent.Flash.Position
        p.Velocity = (playerName.Character.Head.Position - v).unit * -400 + Vector3.new(math.random(-2,2),math.random(-2,2),math.random(-2,2))
        local upforce = Instance.new("BodyForce")
        upforce.Parent = p
        upforce.force = Vector3.new(0, p:GetMass() * script.Parent.Configure.Speed.Value , 0)
        script.Parent.Flash.Light.Light.Visible = true
        wait(0.05)
        script.Parent.Flash.Light.Light.Visible = false
        wait(script.Parent.Configure.ClickTick.Value - 0.05)
        canfire=true

    end
end


local canrel = true
local canAuto = true

if script.Parent.Configure.Auto.Value~=true then
    script.Parent.Activated:Connect(function()
        if script.Parent.Enabled == true then
            if script.Parent.Configure.Ammo.Value > 0 or script.Parent.Configure.InfiniteMagSize then
                fire(playerName.Character.Humanoid.TargetPoint)
                script.Parent.Configure.Ammo.Value = originalAmmo
            elseif canrel==true then
                canrel = false
                script.Parent.Handle.Reload:Play()
                wait(script.Parent.Configure.ReloadTime)
                script.Parent.Configure.Ammo.Value = originalAmmo
                canrel = true
            end
        end
        isActive = true
    end)
else
    script.Parent.Activated:Connect(function()
        if canAuto==true then
            repeat
                canAuto=false
                if canfire~=false then
                    if script.Parent.Configure.Ammo.Value > 0 or script.Parent.Configure.InfiniteMagSize then
                        fire(playerName.Character.Humanoid.TargetPoint)
                        script.Parent.Configure.Ammo.Value = originalAmmo
                        wait(script.Parent.Configure.ClickTick.Value)
                    elseif canrel==true then
                        canrel = false
                        script.Parent.Handle.Reload:Play()
                        wait(script.Parent.Configure.ReloadTime)
                        script.Parent.Configure.Ammo.Value = originalAmmo
                        canrel = true
                    end
                end
            until script.MouseDown.Value==false or script.Parent.Configure.Ammo.Value<=0
            canAuto=true
        end
    end)
end


script.Parent.Unequipped:Connect(function()
    isActive = false
end)