ADS1292: CMRR test issue

Hello,I have tested my system's CMRR,but not quite good,here is my test result:

The test was conducted according to <YY1079-2008>,here post the test circuit;

Then i tested ADS1292FE demo board the same way,here is the result:

;

I,think i should use 4.2V as the Vcm input,because it's the real input;

Here comes my first question:

The ADS1292 FE demo board CMRR test result seems like don't meet the descrition by the white paper <Improving Common-Mode Rejection Using the Right-Leg Drive Amplifier>

Please help me analyze the situation;

My second question is that why in my system after connected the RLD, i have only about 3dB CMRR increase ,but in the demo board it has about 13dB increase which had meet the white paper? and what should i do to increase CMRR about 13 dB when i connect the RLD?

Here post my circuit diagram&my reg value:

After tested the demo board,I did the following test ,i had changed the RLD feed back res(R12) from 110K to 4.7M( C8 was DNP when testing)，but it seems that just have a little influence (about 1 dB) on the CMRR，

that's different from the way I thought it would be; What could be the cause?

Please help to analyze the above reasons,thanks!