Default [Q]System app to user app .

Hi all , I am using a custom rom now . But I want to add a system app( from my stock rom ) to this custom rom . I moved it into my system folder . But it is not working. I think system apps don't work with other roms.

I want to conver that app usable for any device .

Need help .

Sent from my GT-S7562 using XDA Premium 4 mobile app
Hitting Thanks button is much easier than typing Thanks .

Device 1 : SGS Duos GT-S7562
Android ver. 4.0.4
Rom : MightyBoy
Device 2 : iKon ik-A800 (TAB)
Rom : Stock .
Android ver. 4.1.1
SystemUI (s7562) :CriTix v2.0.0

rom for GT-S7562