Inventory organizer isn't working, linked script. What can I do tho fix or remake to work?

At the moment I have a Gui that has 25 slots for items (ImageButtons). There is a script inside the items you pick up that changes the next slot available out of the 25 slots. The problem Im having is when you drop an item it wont fill in the spaces... For example, lets say I pick of 5 different items, that would mean the the first 5 slots are filled. Then lest say I drop the 3rd item which then the script is supposed to move the 4th and 5th item to the 3rd and 4th slot but its not doing so. I was wondering if someone could take a look and give me some advice on what to do hints why I am here.

script inside the items>>>

script.Parent.ClickDetector.MouseClick:connect(function(Player)
    local items = Player.PlayerGui.InventoryGui.Frame.Inventory.Inventory
    for i = 1, 25 do 
        local itm = items:FindFirstChild('Item' .. tostring(i)) 
        if itm.ItemNumber.Value == 0 then
            itm.ItemNumber.Value = script.Parent.ItemId.Value
            itm.Image = script.Parent.PicId.Value
                   break
        end
    end
end)

LINKED!!! Script inside ImageButtons>>>

wait(.8)
local Player = game.Players.LocalPlayer
local Gui = script.Parent
local Observing = script.Observer.Value
local Item = script.Parent.ItemNumber
local Pic = script.Parent.Image
script.Observer.Value.ItemNumber.Changed:connect(function()
    if script.Observer.Value.ItemNumber.Value == 0 then
        Item.Value = 0
            Observing.ItemNumber.Value = Item.Value 
                Observing.Image = Pic
                    Pic = ""
    end
end)