look up in Nook app

[susang]

Love my nexus purchased several months ago!  One minor issue . . . when I'm reading using Nook app you're supposed to be able to highlight a word or phrase then press look up and it'll take you right to Google or Wikipedia (whichever one you chose) for look up without having to type in the search topic.   Less than half of the time the app will have retained the search topic, in which case I have to go back to the my reading material to verify spelling or word order, type it in on the search bar.  What am I doing wrong?