Importing images for a custom menu

[Everest.]

I've made a menu that imports images using DImages and DImageButtons, and on other client's computers the images appear to be missing (checkerboards) I dropped this in the server's shared.lua:
resource.AddFile("vgui/Back.png")
resource.AddFile("vgui/Close.png")
resource.AddFile("vgui/Deposit2.png")
resource.AddFile("vgui/DepositConfirm.png")
resource.AddFile("vgui/DepositCustom.png")
Path is as follows (I have all of my images stored in the vgui folder):

https://imgur.com/a/56CPmgg