How to turn vibration on, in my iPhone?

Okay! So I full have my vibration turned on my iPhone 4 but it still doesn't work and I don't know why? Any suggestions or anyone know the problem

Go to settings, and sounds, make sure that the bar is all the way up so that the vibration is noticeable

Go to settings, then go to sounds and turn on vibrate on ring and silent. Hope that helped.