Raycast-Based Gun Doesn't Work?

This is a script that is supposed to be in a raycast-based gun. However, when I shoot it, nothing happens. Absolutely nothing. There isn't even anything in the output log.

The exception is when I shoot it skyward, when it registers a "Nil value" error for "Hit." This seems to indicate that it's detecting "Hit", but not doing anything afterwards. How do I fix this?

Here's the code:

local tool = script.Parent
local user
local IgnoreList = {"Handle", "Hat"}


tool.Equipped:connect(function(mouse)

   user = {script.Parent:WaitForChild("Handle"), script.Parent:WaitForChild("Handle")}

   mouse.Button1Down:connect(function()

      local ray = Ray.new(tool.AimPart.CFrame.p, (mouse.Hit.p - tool.Handle.CFrame.p).unit*300)
      local hit, position = game.Workspace:FindPartOnRayWithIgnoreList(ray, user)


      local playerhit = game.Players:GetPlayerFromCharacter(hit.Parent) or game.Players:GetPlayerFromCharacter(hit.Parent.Parent)
      if playerhit then
      local humanoid = playerhit.Character.Humanoid
      print(hit.Name)
      if humanoid then
           if hit.Name == "Head" then
            humanoid:TakeDamage(100)
            else
            humanoid:TakeDamage(30)
            end
       end

        -- Settings
       local distance = (position - tool.AimPart.CFrame.p).magnitude
       local rayPart = Instance.new("Part", user)
       rayPart.Name          = "RayPart"
       rayPart.BrickColor    = BrickColor.new("Really blue")
       rayPart.Parent        = game.Workspace
       rayPart.Transparency  = 0.5
       rayPart.Anchored      = true
       rayPart.CanCollide    = false
       rayPart.TopSurface    = Enum.SurfaceType.Smooth
       rayPart.BottomSurface = Enum.SurfaceType.Smooth
       rayPart.formFactor    = Enum.FormFactor.Custom
       rayPart.Size          = Vector3.new(0.2, 0.2, distance)
       rayPart.CFrame        = CFrame.new(position, tool.AimPart.CFrame.p) * CFrame.new(0, 0, -distance/2)

       game.Debris:AddItem(rayPart, 0.1)
       end
    end)
end)