Vectorforce help

I’ve made this script for a jetpack system

local VF = Instance.new("VectorForce")
local speed = 100
VF.Parent = script.Parent:WaitForChild("HumanoidRootPart")
VF.Attachment0 = VF.Parent:WaitForChild("RootRigAttachment")
game:GetService("RunService").RenderStepped:Connect(function()
	if game:GetService("UserInputService"):IsMouseButtonPressed(Enum.UserInputType.MouseButton1) then
		if speed < 200 then
			print(speed)
			speed = speed * 1.01
			VF.Force = game.Workspace.CurrentCamera.CFrame.LookVector * speed
		else
			speed = 200
		end
		VF.Force = game.Workspace.CurrentCamera.CFrame.LookVector * speed
	elseif game:GetService("UserInputService"):IsMouseButtonPressed(Enum.UserInputType.MouseButton2) then
		if speed > 100 then
			print(speed)
			speed = speed / 1.01
		else
			speed = 100
		end
		VF.Force = game.Workspace.CurrentCamera.CFrame.LookVector * speed
	end
end)

It appears that when the gravity is set to zero, the only coordinate the vector force moves at was the Y coordinate.
How do I fix that?
Thanks.