Please note that at this stage we don't support custom ROMs with Viber. Running Viber on a custom ROM results in various side effects (sometimes total lack of functionality), but we can't afford to support all custom ROMs out there. We are continuously working to adapt Viber to more and more ROMS, but meanwhile - you might want to contact the ROM developer for further support - they may be able to resolve this issue.

Meanwhile, may we ask what exactly is the problem you're experiencing when using Viber on Dark Knight 4?

@ezra_29 -
What error exactly occurs when you try to install? Please try to elaborate, or even add a quick screenshot...

@azrash -
Please note that Viber does not work with satellite location (GPS), but rather with cellular, tower location.
However, what you're describing is still an error (unless I misunderstood it). I kindly ask you to report this issue to our support team so they could understand its source better and hopefully help you. Here's the link: http://bit.ly/ukGVJ0

Thanks in advance