ADE7763 Vrms Register Reading Problem

Hello Friends,

I am Using ADE7763 for reading of Vrms,IRms and Power. I have Successfully establish SPI Communication bet'n renesas MCU and ADE7763().By reading the default values of registers.

After Setting initial configuration of ADE7763, i am reading Vrms Register(0x17) at 150VAC.
But when i did not give Channel 2 Vrms Input, then i got some decimal values on the Screen.
when i give Channel 2 Input and i increase VAC input 150 -200-250, it's reading are varying but in a very small range.
but when i decrease input form 150-100-50-30, my reading are not decreasing it steady at 150VAC.

so to trouble shoot this problem i check the hardware and Channel 2 input,it is varying from minimum to maximum range till 0.5VAC(Gain = 1 at channel 2). so i think my hardware is perfect.

so please help to trouble shoot this problem.
My Initial setting to ADE7763 is as follows.

Gain register(0x0F) = 0x00
Mode Reg(0x09) = 0x000C
interrupt Enable(0x0A) = 0x0010

So please help.

Check Rev C spec starting page 23

I have already seen the fully datasheet of ADE7763 and it's specifications, but i did not get anything about my the problem.

Please reply.