The preview of my building tool is flying off to my face?

I'm creating a tool to place blocks. I started by creating a preview of the block. When I finished, I noticed that the preview was a bit buried, so I tried to fix it. But then when I made the changes, the block would fly towards the camera. How do I fix this problem, while making the preview entirely above ground?

------------------
--[DECLARATIONS]--
------------------

----/[SERVICES]\----

----/[MAIN]\----
local plr = game.Players
local tool = script.Parent

----/[VARIABLES]\----
local ghostBlock

----/[CONSTANTS]\----
local CELL_SIZE = 1
local CON_NAME = "[".. plr.Name .."/BuildTool/Local]"

----/[BLOCKS]\----
local woodBlock1 = {
	Size = Vector3.new(4,1,4),
	Color = BrickColor.new("CGA brown"),
	Material = "WoodPlanks",
	Transparency = 0,
	Reflectance = 0,
	
}

--------------------
--[INITIALIZATION]--
--------------------

---------------
--[FUNCTIONS]--
---------------

--Snaps the position to the grid
function SnapPosToGrid(rawPos, size)
	--Gets the raw position and snaps it to the grid defined by the cell size
	local snappedPos = CFrame.new(	rawPos.X - rawPos.X % CELL_SIZE,
									(rawPos.Y - rawPos.Y % CELL_SIZE) + size.Y/2,
									rawPos.Z - rawPos.Z % CELL_SIZE)
		
	--Return the position
	return snappedPos
end

--Create ghost
function CreateGhostBlock(block)
	--Create part and customize it
	local ghost = Instance.new("Part",workspace)
		ghost.Size = block.Size
		ghost.BrickColor = block.Color
		ghost.Material = block.Material
		ghost.Transparency = .5
		ghost.Anchored = true
		ghost.CanCollide = false
		ghost.Locked = true
		ghost.Name = "Ghost"
		
	--Return the created part
	return ghost
end

--The mouse has moved, create a ghost block
function MouseMoved(mouse)
	--If the target of the mouse is not permited, don't do anything
	--if mouse.Target.Name == "Ghost" then return end	
	
	--Get the position of the mouse and snap it to the grid
	local mouseHit = mouse.Hit.p
	local gridCFrame = SnapPosToGrid(mouseHit,woodBlock1.Size)
	
	--Create a ghost part if it doesn't exist and change the position of it
	if not ghostBlock then
		ghostBlock = CreateGhostBlock(woodBlock1)
	end	
	ghostBlock.CFrame = gridCFrame
end

------------------
--[SCRIPT LOGIC]--
------------------

--The tool has been equipped
tool.Equipped:Connect(function(mouse)
	--Mouse has not been found for some reason
	if not mouse then warn(CON_NAME..": Mouse has not been found!") return end
	
	local mouseMoved = mouse.Move:Connect(function() MouseMoved(mouse) end)
	
	--Tool has been unequipped
	tool.Unequipped:Connect(function()
		--Disconnect Events
		if mouseMoved then mouseMoved:Disconnect() end
	end)
end)

Ok, I found it out. You need to add the ghost part to the mouse filter.

--Create a ghost part if it doesn't exist and change the position of it
if not ghostBlock then
	ghostBlock = CreateGhostBlock(woodBlock1)
	mouse.TargetFilter = ghostBlock
end