Derma Issues

Hey everyone, I’m having some issues with Derma currently, I’m not new to Lua although I’ve only started Derma today (I never wanted to go through it, but here I am)

Now this is my code, some will seem familiar to those who view the wiki.

function DemoMenu ()
    MainMenu = vgui.Create( "DFrame" )
    MainMenu:SetPos( 350, 100 )
    MainMenu:SetSize( 900, 700 )
    MainMenu:SetTitle( "Menu" )
    MainMenu:SetBackgroundBlur( true )
    MainMenu:SetVisible( true )
    MainMenu:SetDraggable( true )
    MainMenu:ShowCloseButton( true )

    local DPanel = vgui.Create( "DPanel" )
    DPanel:SetPos( 360, 110 )
    DPanel:SetSize( 800, 600 )

    local DLabel = vgui.Create( "DLabel", DPanel )
    DLabel:SetPos( 400, 50 )
    DLabel:SetText( "I'm a DLabel inside a DPanel! :3" )
    DLabel:SetDark( 1 )
concommand.Add("OpenDemoMenu", DemoMenu )

Now my issue being is that the DPanel and DLabel aren’t actually connected to the Frame, E.G It appears behind the Frame, and even when I close the frame it remains.

Thankyou in advance!

local DPanel = vgui.Create( "DPanel",  MainMenu)

Can’t believe I missed that, it’s shameful, Thankyou!