Post Multitasking not working

On my samsung galaxy s4 i9505 my multitasking view, and task manager doesn't work. I'm currently running Omega v19 rom, but it didn't work on Flight v5 either. I also had some problems after rooting the stock rom. When i try to open multitasking bar, it just gives a message that system UI has stopped. Also i noticed the background sometimes resetting to stock. What can I do to fix this? It is very annoying... I added a screenshot of the crash message. Click image for larger version

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PS. sorry for bad english