Both of the remote fobs can only unlock.
The door lock works fine using the main switch on the driver side control panel. It also works fine using the key.
When using the key fob to lock, nothing happens and no sound can be heard at all.
I hooked up the red lead on a digital multimeter to the battery positive terminal, and used the negative lead from the meter to probe either contact on the connector while pressing the key fob:

2003-2007 Accord (2004-2008 TSX) door lock actuator connector (harness-side)

When pressing the lock button on the fob, the meter registers nothing.
When pressing the unlock button (two presses--because the driver side is disconnected) on the fob, I get the following readings:
The right contact:
Trial 1:
Low: -0.026 V
High: 0.296 V

Trial 2:
Low: -0.040 V
High: 0.304 V

The left contact:
Trial 1:
Low: -0.044 V
High: OL

Trial 2:
Low: -0.039 V
High: OL

What should the readings be? How should I be testing this problem?
Actuator part #: 72155-SDA-A01