Default Need help in flashing LGSystemUI.apk of another rom into stock

So, i am on stock kitkat.
i want LGSystemUI.apk of the below rom to work in stock kitkat.
http://lgviet.com/forum/threads/rom-...ix-link.20564/
But whenever i do so i get an error "unfortunately android.systemui.com has stopped working"
How to solve this problem?
Thanks