Attempt to index nil with visible

Ive just changed my normal gui frames to scrolling frames, the layout and order of these have stayed the same throughout the gui, however now im getting the following error:


Even though from what I can see theirs no reason at all for this, this is the script:
image

This is what it prints. clearly showing the correct name:
image

This is how the gui is layed out (skinsframe is set as mainframe.skins):
image

:WaitForChild(), for UI elements, from that I mean something like:
local Mainframe = Player:WaitForChild("PlayerGui"):WaitForChild("MainGui"):WaitForChild("Mainframe")

Nvm, stupid mistake, forgot to delete the previous skins frame you can see at the top under the core script. not sure how ive missed that