Arlo Doorbell with existing chime does not ring, makes a constant hum

[TForman42]

I have followed the simple instructions for installing the doorbell yet can't seem to get it to work.  When I connect it to my existing doorbell, it does not ring when you push the Arlo Doorbell, instead there is a constant hum coming from the existing doorbell unit.  This happens when I turn the power back on.  Once I turn it off, the buzzing disappears.  I have tried putting the switch in all 3 positions (A, B and C) and it does the same in all three.  Can anyone help me figure out what I'm doing wrong?

[JamesC]

TForman42,

It sounds like your existing Chime may not be compatible with the Arlo Doorbell. Take a look here for more information on existing chime requirements: How do I set up my Arlo Audio Doorbell to trigger my existing chime?

JamesC