Default Need help, with Lockscreen

hey guys, iam having problem in changing Lockscreen wallpaper, i can only select from xperia wallpapers, if i select any other custom image/wallpaper it doesnt change at all.... any help? any app that can change the lockscreen wallpaper
XPERIA M(SS)

Currently Running Stock 4.3(15.4.A.1.9) With Unlocked Bootloader and Root DEODEXED