SQLITE query returns no result

I have this query in my LoginAdapter class:

public Cursor FetchRow (String username){

  return db.query("LOGIN",new String[]{"ID","USERNAME","PASSWORD","COURSE","EMAIL","STUDENT_NAME"},"USERNAME" + "='" + username + "'",null,null,null,null);

}

When I call it from another activity the emulator opens the activity but with no results:

 String username = bundle.getString("username");

    loginDataBaseAdapter.FetchRow(username);