DockWidget Plugin GUI problems

So I’m having a problem with this PluginDockWidget, to start, it won’t open after I close it unless I save it as a plugin again. The other problem is that it won’t set the size correctly, the size it will appear as will be the size it last closed as.
I can’t find anything about this, could anyone help?

Here is the code:

local ChangeHistoryService = game:GetService("ChangeHistoryService")

local Toolbar = plugin:CreateToolbar("Procedural Animations")
local MainButton = Toolbar:CreateButton("MainButton", "Open Panel", "http://www.roblox.com/asset/?id=44360456")


--- Shortcuts
local RGB = Color3.fromRGB

local function Startup()
	Mouse = plugin:GetMouse()
	Interface = plugin:CreateDockWidgetPluginGui(
		"Procedural Animation",
		DockWidgetPluginGuiInfo.new(
			Enum.InitialDockState.Float,
			true,
			true,
			650,
			350,
			483,
			250
		)
	)
	Interface.Title = "Procedural Animation Editor"
	
	
	--- This isn't really used, but is a backup
	local function AltCreate()
		--- Create GUI Parts
		FrameGUI1 						= Instance.new("Frame", Interface)
		FrameGUI1.Size 					= UDim2.fromScale(1, 1)
		FrameGUI1.BackgroundColor3 	= RGB(41, 41, 41)
		FrameGUI1.BorderSizePixel 		= 0
		
		--- Top Bar
		TopBar							= Instance.new("Frame", Interface)
		TopBar.Size						= UDim2.new(1, 0, 0, 13)
		TopBar.BackgroundColor3		= RGB(66, 66, 66)
		TopBar.BorderSizePixel			= 0
		
		
		--- Left Side Section
		
	end
	AltCreate()
end



--- Open panel
MainButton.Click:Connect(function()
	Startup()
end)