For an overview of how to program an LRA transmitter to an LRA receiver, please consult one of these FAQ documents:
The process for programming any LRA transmitter is the same until you get to the part where you need to trigger the transmitter/sensor. Since the LRA-DSTX is a PIR motion-based sensor, it's easy to accidentally trigger the transmitter before you are ready to do so. Any movement in front of the sensor lens will trigger it. To prevent this, please ensure you are following the instructions per the user manual: LRA-DSTX User Manual.
Useful Tip: the LRA-DSTX has a switch (see user manual) for turning the "photocell" on or off. By default, the photocell should be switched to "off" which means the sensor will work during daytime and nighttime operation. Switching the photocell to "on" will make the sensor only function at night.