AD8232 input impedance for YY0885-2013

HELLO,

1  designed one Dynamic holter  with AD8232.

when signal input LA &RA directly,I can get correct output.

if input signal is sine wave ,10Hz  5mV,  gain=380, I can get output

But  according to the national standard YY 0885-2013, the input impedance is tested. The following is the test circuit.

if input signal is sine wave ,10Hz  5mV,  gain=380, I get wrong output.

I wonder why? Thanks!