I get file not found exception trying to open a file in my assets folder (android)

I get file not found exception trying to open a file in my assets folder
(android)

I have a file in my assests folder. I use the following code to open it,
but I get a file not found exception.
super.onCreate(savedInstanceState);
setContentView(R.layout.bar_page_lo);
appContext = getApplicationContext();
InputStream ins;
ins = appContext.getResources().getAssets().open("bar-data.json");
any Ideas?