Local Notifications don't work

Hello, i have one question about local notifications plugin.

I have a problem because when my phone is in sleep mode, the notifications show sometimes and sometimes not.

When i use again the phone, the notifications appear with delay time and sometimes doesn’t sound or appear again.

I like to know if someone have the idea whats happening and how can i solve that.

My celphone is an Android Blu life one x2.
I probe in other phones like samsung and motorola and happen the same thing.

I wish someone can help me

Thank you