Working on updating my UI

[Kupotek]

Hello, I'm the author of longtime game UI, Panther, right here on Wowinterface since 2008... I came back to WOW after a few years and am running into a few errors I'm hoping someone can help me fix as I hope to release a new version of the UI soon.

1. In my welcome screen bugsack is giving me a SetBackdrop error, this is the code in my welcome screen addon:

f:SetBackdrop( { bgFile="Interface\\Addons\\DialogFrame\\Smoke", insets={left=4,right=4,top=4,bottom=4}, tileSize=16, tile=false, edgeFile="Interface\\Addons\\DialogFrame\\Border", edgeSize = 8 } )

THE ERROR ITSELF IS:

6x PantherWelcome\PantherWelcome.lua:13: attempt to call method 'SetBackdrop' (a nil value)
[string "@PantherWelcome\PantherWelcome.lua"]:13: in function <PantherWelcome\PantherWelcome.lua:8>

Locals:
(*temporary) = nil
(*temporary) = PantherWelcome {
0 = <userdata>
}
(*temporary) = <table> {
bgFile = "Addons\DialogFrame\Smoke"
tileSize = 16
tile = false
edgeSize = 8
edgeFile = "Addons\DialogFrame\Border"
insets = <table> {
}
}
(*temporary) = "attempt to call method 'SetBackdrop' (a nil value)"
f = PantherWelcome {
0 = <userdata>
}