Requesting BATTERY2 message

QGroundControl 3.4.2
ArduCopter 3.6.1

I do see BATTERY2 message in QGroundControl MAVLink inspector, but I cannot get it from a companion computer.

The companion computer does request MAV_DATA_STREAM_EXTRA3 with 2 Hz frequency. It does get most of MAV_DATA_STREAM_EXTRA3 messages, including BATTERY_STATUS, TERRAIN_REPORT, and VIBRATION, but BATTERY2 is not there. Why is that?

It was my error. BATTERY2 message was sent by ArduPilot but was not parsed correctly.