FastCast not creating bullet?

---///VARIABLES\\\---
local RepStorage = game:GetService("ReplicatedStorage")
local Modules = RepStorage:WaitForChild("Modules")
local Objects = RepStorage:WaitForChild("Objects")

local FastCast = require(Modules:WaitForChild("FastCastRedux"))

local FireRemote = script.Parent:WaitForChild("Fire")

local Hook = Objects:WaitForChild("Hook")

local Caster = FastCast.new()

local Behavior = FastCast.newBehavior()

local Params = RaycastParams.new()
Params.FilterType = Enum.RaycastFilterType.Exclude
Params.FilterDescendantsInstances = {}

Behavior.RaycastParams = Params
Behavior.Acceleration = Vector3.new(0, -50, 0)
Behavior.MaxDistance = 1000
Behavior.HighFidelityBehavior = FastCast.HighFidelityBehavior.Default
Behavior.HighFidelitySegmentSize = 0.5
Behavior.CosmeticBulletTemplate = Hook
Behavior.CosmeticBulletContainer = workspace.Cache
Behavior.AutoIgnoreContainer = true

Caster.LengthChanged:Connect(function(ActiveCast, lastPoint, rayDir, displacement, segmentVelocity, cosmeticBulletObject)
    
    local NewPos = lastPoint + (rayDir * displacement)
    
    cosmeticBulletObject.Position = NewPos
    
end)

Why is it saying that the cosmeticBulletObject is nil?