Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Problems with this system

I got the annunciator w sensor and 2 xtra sensors. Annunciator signal tone high pitch, a freq that i can hardly hear, low vol. Individual sensor alarms could not be set nor recognized. All sensors were set for 30 feet. 1 sensor functioned only at 3'. Another at about 0-10. The other usually did not function. No sensor functioned consistently. The best sensor failed completely to register my walking in front of it about 20% of the time. As a personnel intruder system, this set i got was useless. Sent it back to Amazon.