ERA-DCKIT-2 
Currently, there are three available LRA receivers, the LRA-DCRX, LRA-DCRXS, and the LRA-VPRX.
Ensure a "Sound" Mode is Selected for the Receiver
Check to ensure "sound" mode is turned on for the receiver. For each of the receivers, there are three modes of operation. For the LRA-DCRX and LRA-DCRXS the three operational modes are 1) sound only, 2) sound & flashing strobe, and 3) flashing strobe only. For the LRA-VPRX, the three operational modes are 1) vibration & sound, 2) vibration only, and 3) sound only. If you are not getting sound from any of these receivers, check to make sure you have a sound mode activated. * See the illustrations below to locate the operation mode selector switch.
Ensure Volume is Turned Up
Of the three receivers, the LRA-DCRX is the only one with a volume control knob. To access the volume control, open the front cover. Locate the volume knob/wheel, and turn to the right to ensure the volume is turned up.