Set Listener for Items inside one tab

Hi, I'm trying to addTextChangedListener for a EditText inside one of the views and getting NullPointerException.
I've tried everything, but all of them was dead-end
Can someone help me?!

Need to do:
"There is a EditText inside ONE of the views that I need to listen for any text entry"

Faced:
"NullPointerException happens when the program reaches the editSearch.addTextChangedListener"

Tried:
"Adding listener when tab changed to existing element"
"Adding listener inside onCreate beside the initUI method"
"Adding listener after the tab appeared on UI"