This SelectionBox isn't coming existent or something?

I'm trying to make a tool that, while it is equipped and the player holding the tool's mouse is over an unlocked part, a SelectionBox is created on the part.

It's a LocalScript directly in a tool (without RequiresHandle):

repeat wait() until game.Players.LocalPlayer ~= nil
local p = game.Players.LocalPlayer

local holding

local mouse = p:GetMouse()
local target = mouse.Target

script.Parent.Equipped:connect(function()
    holding = true
end)

script.Parent.Unequipped:connect(function()
    holding = false
end)

while holding == true do
    if target ~= nil then
        target.Changed:connect(function(newTarget)
            target = newTarget
            if target.Locked ~= true then
                local box = Instance.new("SelectionBox", target)
                box.Adornee = target
                box.LineThickness = 0.1
                box.Color3 = Color3.fromRGB(255,128,0)
            end
        end)
    end
end