ADE7880 different error per Phase

Hello AD experts,
I am working on 3 phase electric meter. with unity gains and Zero offsets.

The input parameters:
Vrms = 220 V with 997 divider circuit                           >>>> adc  reads 220.66 mv
Irms = 5 A with 300 CT and burden = 2*8.2                 >>>>>adc reads 273.33 mv
power factor is .5 

so the injected power is 550 watt.

The xWATTHR error differs than the reference machine (CF pulse) error. Also, this error vary from phase to another.

Total phases error is 4.1 %

AWATTHR  ----------- +0.2-------    4.3

BWATTHR  ------------ +0.002   (accepted) 4.1002

CWATTHR  ----------- -0.2 ----- 3.9

best regards
Hossam