Why are my tabs not displaying on my panel...

I’m doing something wrong but I have stared at this thing for an hour. You’ll see it in probably 5 seconds.


PanelTable = {}


 
function CreatePanel()
        PanelTable.base = vgui.Create("DFrame")
        PanelTable.base:SetSize(1800, 1000)
        PanelTable.base:SetPos(ScrW() / 2 - PanelTable.base:GetWide() / 2, ScrH() / 2 - PanelTable.base:GetTall() / 2)
        PanelTable.base:ShowCloseButton(true)
        PanelTable.base:MakePopup()
        PanelTable.base:SetVisible(true)
        PanelTable.base:SetDraggable(true)
        PanelTable.base:SetTitle("Instructor Panel")
       
        PanelTable.MyTabs = vgui.Create( "DPropertySheet", PanelTable.base )
        PanelTable.MyTabs:SetPos( 50, 30 )
        PanelTable.MyTabs:SetSize( 1700, 900 )
        PanelTable.MyTabs:AddSheet( "Fire Panel", PanelTable.FirePanel, nill, false, false, "Fire here" )
        PanelTable.MyTabs:AddSheet( "Main", PanelTable.MedicPanel, nill, false, false, "Medic here" )
       
        PanelTable.FirePanel = vgui.Create("DPanel", PanelTable.MyTabs)
        PanelTable.FirePanel:SetSize(1700, 900)
        PanelTable.FirePanel:SetPos(10,30,1)
        PanelTable.FirePanel:SetDrawBackground( false )
		
		 
		PanelTable.MedicPanel = vgui.Create("DPanel", PanelTable.MyTabs)
		PanelTable.MedicPanel:SetSize(2000, 900)
		PanelTable.MedicPanel:SetPos(30,30,1)
		PanelTable.MedicPanel:SetPaintBackground( false )
		
		PanelTable.Button99 = vgui.Create( "DButton", PanelTable.MedicPanel)
		PanelTable.Button99:SetSize(200,100)
		PanelTable.Button99:SetPos(199,199,3)
		PanelTable.Button99:SetText("Finally")
	   
	   
        PanelTable.tblButtons = {}
        PanelTable.Button1 		= vgui.Create( "DButton", PanelTable.FirePanel )
        PanelTable.Button1:SetSize(200, 100)
        PanelTable.Button1:SetPos(10,10,3)
        PanelTable.Button1:SetText( "Begin Fire Scenario" )
        PanelTable.Button1.DoClick = function (self)

Firstly, you’ve spelt “nil” as “nill”, I’m really not sure if that will work or not.
Secondly, you are calling AddSheet before the actual panels are created.

Thanks for the quick response. That was it. I am dumb.