Instruct: Classify a review into positive or negative sentiment.
Query: Worked at first now it's no good

It worked for the first week and then stopped working when my dog barks. The battery is working and it's full. I test it and it works when I do it but not when she barks. I think it might be because she has a high pitched bark because when my other dog, who has a low pitch, barks and he's near her it sets off the spray device.