Sorry to hear that. If you gave us more information and explained the problem we might be able to help. A screenshot showing the exercise, your answer and the response from the program that grades the answers would help.
I really would love to learn how to add DL screenshots in my questions/replies/comments. I searched in the discussions but no luck. Can you point me to the right thread? Thanks a million.
It's not possible to add them to a Duolingo comment directly -- you will have to upload them to a website somewhere (e.g. an image sharing host) and then put an URL/link to the image into a comment.
Thanks so much! Doing some digging, I did find the threads that explain how to add pictures and how to format text (boldface, italics, highlighter, links and whatnot), which are quite helpful. These discussions are more easily found doing a search for duolingo formatting, in case anyone is interested.