Why does my script not recognise that a child has been added to a folder?

So I've been making a placement game where you click on an area and it will place a building. It works on a grid system and so I have string values in each clicker part that correspond to their location on the grid, e.g C1, D5, J9. When a player clicks on the part, the string value within that part will move to another folder in the ReplicatedStorage so that I can compare it with a string value that is within a pre-built building at that location. This allows me to move their selected building to the CFrame of the pre-built building. However, whenever I use the GetChildren() function (or similar like FindFirstChild) on the folder in the ReplicatedStorage, it comes back with an error saying GridPosition is not a valid member of Folder. I can see in the explorer tab that the string value definitely is in the folder. The code below is me trying to compare both StringValues. GridPosition is the name of the string value inside every clicker part, and GridPositioning is the string value inside every pre-built room. What am I missing?

game.Workspace.ClickerEvent.OnServerEvent:Connect(function()
	
	local levels = game.ReplicatedStorage.Exoskeleton:GetChildren()
	
	for i = 1, #levels do
	
		local rooms = levels[i]:GetChildren()
			
		for i = 1, #rooms do
	
			local roomlocation = rooms[i].GridPositioning.Value
				
			wait(4)
			if game.ReplicatedStorage.TemporaryClick.GridPosition.Value == roomlocation then
				local room = game.ReplicatedStorage.Rooms["Test room"]
				local placed = room:Clone()
				placed.Parent = game.Workspace.UserPlaced
				placed:SetPrimaryPartCFrame(CFrame.new(rooms[i].CFrame))
			end			
		end	
	end	
		
end)