My Dakota Alert IR-3000 seems intermittent as a door sensor.
The sensor is usually mounted above the doorway and aimed down to reliably detect visitors walking through the doorway. The PIR masking strips may be removed if the narrow detection pattern needs to be widened. If you are using it more then 50’ away from the receiver you might have to option the power to “high” in the IR3000. Please set all 8 of the frequency switches to 0 or OFF on the transmitter and receiver while testing. Use only a good quality alkaline battery measuring at least 9 volts with a volt meter.