A script meant to launch a fireball isn't working, but no errors appear when i run it?

I'm making a game where if you press 'F' you launch a fireball. This is the script i'm using

game.Players.PlayerAdded:wait()
Player = script.Parent.Parent.Parent -- Gets LocalPlayer 

Player.CharacterAdded:wait()
Character = Player.Character

Mouse = Player:GetMouse()

function onKeyDown(key) 
    if key:lower() == "f" then 
        local ball = Instance.new("Part") 
        ball.TopSurface = "Smooth" 
        ball.BottomSurface = "Smooth" 
        ball.Shape = "Ball" 
        ball.Transparency = 0.7
        ball.BrickColor = BrickColor.new("Bright red") 
        ball.Parent = game.Workspace 

        local fire = Instance.new("Fire") 
        fire.Parent = ball 
        fire.Size = 12 
        fire.Heat = 0 
        fire.Color = BrickColor.new("Really black")

        local velocity = Instance.new("BodyVelocity") 
        velocity.maxForce = Vector3.new(999, 999, 999)
        velocity.velocity = Character.Head.CFrame.lookVector * 50
        velocity.Parent = ball  

        ball.Position = Character.Head.Position + 2
        ball.CFrame = Character.Head.CFrame * CFrame.new(0, 0, 10)
    end 
end 

Mouse.KeyDown:connect(onKeyDown)
-- this is placed in a tool inside the starter pack

it doesn't show any errors when i run it, but it doesn't work Can anyone explain what the problem is? I'm pretty new to roblox lua scripting, so sorry if this is a stupid question