Why does my local script just detect the Baseplate?

This script places bricks but it can only place them in the Baseplate, if the mouse is pointing another part it does nothing. there aren't any errors in the output. here is the code:

plr = game.Players.LocalPlayer
repeat wait() until plr.Character
char = plr.Character
m = plr:GetMouse()
c = workspace.CurrentCamera
posX = script.posX
posY = script.posY
posZ = script.posZ

local p = Instance.new("Part")
p.Parent = workspace
p.Size = Vector3.new(4,1,2)
p.Anchored = true
p.Transparency = 0.5
p.CanCollide = false
p.Massless = true
p.Color = Color3.fromRGB(255, 89, 89)
p.Material = Enum.Material.Brick
p.CastShadow = true
p.Reflectance = 0
p.Name = "Brick"
p.Archivable = true
p.Locked = false
p.BackSurface = "Smooth"
p.BottomSurface = "Smooth"
p.FrontSurface = "Smooth"
p.LeftSurface = "Smooth"
p.RightSurface = "Smooth"
p.TopSurface = "Smooth"
p.CollisionGroupId = 0
p.Shape = "Block"

game["Run Service"].RenderStepped:connect(function()
	if m.Target.Name == "Brick" then
		posX.Value = m.Hit.p.X
		posY.Value = char.HumanoidRootPart.CFrame.Y-2.5 --this was different at first but I changed it to be the same as the baseplate (it didn't work)
		posZ.Value = m.Hit.p.Z
	end
	if m.Target.Name == "Baseplate" then
		posX.Value = m.Hit.p.X
		posY.Value = char.HumanoidRootPart.CFrame.Y-2.5
		posZ.Value = m.Hit.p.Z
		p.CFrame = CFrame.new(posX.Value,posY.Value,posZ.Value)
	end
end)

local spl = Instance.new("SelectionPartLasso")
spl.Parent = char
spl.Humanoid = char.Humanoid
spl.Part = p
spl.Visible = true

m.Button1Down:connect(function()
	local p2 = p:Clone()
    p2.Parent = workspace
    p2.Size = Vector3.new(4,1,2)
    p2.Anchored = true
    p2.Transparency = 0
    p2.CanCollide = true
    p2.Massless = false
    p2.Color = Color3.fromRGB(255, 255, 255)
    p2.Material = Enum.Material.Plastic
    p2.CastShadow = true
    p2.Reflectance = 0
    p2.Name = "Brick"
    p2.Archivable = true
    p2.Locked = false
    p2.BackSurface = "Smooth"
    p2.BottomSurface = "Smooth"
    p2.FrontSurface = "Smooth"
    p2.LeftSurface = "Smooth"
    p2.RightSurface = "Smooth"
    p2.TopSurface = "Smooth"
    p2.CollisionGroupId = 0
    p2.Shape = "Block"
    local valuee = Instance.new("StringValue")
    valuee.Name = plr.Name
    valuee.Parent = p2
end)