ad8232 failure

I use AD8232 as the ecg AFE to capture the ecg wave along with several bcg and scg. when itook the whole system to a hospital , i found the ecg unit didn't work as expected

as showed with the pic below , this wave is captured by my 24-bit adc and the cursor value has been divided  to scare the y-axis to [0 65545], The negative rail is about 114 .and this pic shows that the samples has a line frequency coupled in  it. and the minimum sample reached the negative rails.

is  there anyone  who can help me with this issue pls. thank  you  very much