how to change the "BIG" folder background?

[6thDAY]

hey guys, Im having trouble changing the background when you opened a folder. I'm not talking about the folder icon background, or even the background where the icons are placed inside the folder. I'm talking about the homescreen wallpaper background. Whenever I opened a folder, the background changes to black. I've already changed the FolderSwitcherBG.png and FolderIconBG.png. Those 2 work just fine, but not the homescreen background.

I've already set my wallpaper from my theme as the default homescreen background but still nothing.

However, when I dont use my theme, and use the default iphone theme, when I open a folder, the wallpaper from my theme shows up. But then when I use my theme again, the folder background changes back to black.

Thanks

[6thDAY]

no one knows?....

I searched around and found:
Folder switching bg help!.

I made a copy of HomeBackground.png and put it in //var/stash/Themes/xxxx.theme/Bundles/com.apple.springboard, but still nothing.

BTW I'm on 4.1

thanks!