The puzzle isn't accepting either Guinea or Guyana as an answer. It only accepts both names with the slash between them. How can anyone possibly guess that that's how we have to answer?
Actually, it doesn't require the slash, but it does require both names, and requires that they be in alphabetical order. Can you either make it so that entering one of the correct answers checks that one off, or at least modify the instructions to note that one line has two possible answers and they both need to be entered. I can't tell you how many times I typed in each of the names individually and couldn't figure out why it wouldn't accept them.