If the scroll bars don't skin and you have bought ObjectDesktop then uninstall WBlinds first. Reboot. Then reinstall WBlinds using StardockCentral (SDC). Reboot and it should work.
If you already installed ObjectDesktop then check the WindowBlinds configuration. You may have disabled scrollbar skinning. Also, some scroll bars (even those of some MS programs) cannot be skinned, because they are drawn by the program and do not use standard scroll bars.