How to enable wallpaper setting in iOS 4.x

Sometimes right after the jailbreaking process the Wallpaper feature in iOS 4.x is gone bad,
means that user does not have a choice to choose different picture for each home screen and lockscreen :





But there is one workaround to solve this issue as following :
1. SSH to \System\Library\CoreServices\Springboard.app and edit the file N82AP.plist
    (You need plist editor for editing)
2. add this following xml content :

    <key>homescreen-wallpaper</key>
    <true/>

3. Save the file N82AP.plist and respring and enjoy !!