ADG726 cannot switch off when test 4-wire resistor

Use 2 ADG726 ICs to switch on-off to test 4-wire resister .  if '/EN' pin set '0'  A0-A3 set to '0', it works well , And we can measure resistor with 4-wire , but if '/EN' pin set '1'  A0-A3 set to '0' ,   we still can measure resistor with 4-wire , but change to 2-wire test , it cannot measure resistor . it is very interesting ,  from the data sheet , we cannot find any useful info to solved it . please help!!!

Thanks  for ADI hard working guys.