Home alarm system not working!

My sister has told me that her home alarm system is not working. This is weird as it is just working fine for my home. We are using the same brand of home alarm system.

I know that her neighbor is very noisy and even at night they will have gathering. She told me that her neighbor are not local people. They are children and adults plus old folks too.

She has come over my place to stay over but she prefers to stay at her home. She is staying at apartment and the security is not good.