5 cell battery/1 cell peaking before others. HELP

[Sming250r]

I'm using a Hyperion 720i net 3 charging a truerc 8000mah pack. when i connect everything it shows 1 cell at 4.20 and the rest at 3.91-3.92. Even when i leave the balancer on for a long time(over night) it does not change the voltage much at all..I am wondering if i would have better luck using a seperate balancer and charging it that way.

Any help or suggestions would be great!

Thanks