Multitasking bar & Folders Backgrounds won't change

Hey guys. I got an iPhone 4 just yesterday (ios 4.1) and it is now jailbroken with Greenpois0n. I managed to get winterboard and everything works fine except for when I wanna change the background for my folders and multitasking bar. I tried different themes and both summerboard and winterboard modes but no luck there.

Anyone else has the same problem or does it have to do with my firmware?

While I'm at it, anyone knows any good HD themes for springboard?

Thanks!