Setting different wallpapers with GPO for two different OU's
I have a School wallpaper that is set in an OU called pupils which has all the pupil accounts. This GPO sets the desktop which is in a shared area. Have recently created a new OU with compputers in for a new suite, I would like the wallpaper to be different in those PC's so created a GPO setting the wallpaper I would like and enforcing it so its the last GPO thats read. But any logons always set the wallpaper in the Pupil OU and I cant figure out why.
I am thinking I may have to resort to a logon script which I dont really want to do rather keep it all in a GPO. If anyone has any nifty logon scripts for setting the desktop they would be handy.