Re: knock feature is not working
We are not sure what device you have as we can't see it from here?
More specifics are better and will get you better help and sooner.
"Knock" is most often an Android term for what we on Windows Phone most often call Double Tap to Wake. See the confusion?
If it applies to Android, maybe try our sister site and include the model name, OS version and any changes you might have made in terms of mods...
Ask a Question - Android Forums at AndroidCentral.com
Or join this site to get the reply button privileges and add the same details about your Windows Phone in this thread...
You could also try a web search:
knock to wake - Bing Add your model name for better results.
I will say my 1520.3 is a bit fussy. It wants a certain cadence. neither too fast nor too slow. I've had to train myself a bit on this screen, whereas others weren't so narrow on what they accepted. Also if you are having proximity sensor issues that can prevent the double tap from being utilized.