I want to thank the person who left a clear report on what they saw as the problem, and while I have no way of knowing who they are, perhaps the next person with the same problem will click through to the comments and find out. They wrote:
"Sometimes these words don't need accent marks to counted correctly and in other questions like this one they do."
The marks you can make with the apostrophe key (') on the US keyboard is the Klingon letter qaghwI'. It's a full letter in its own right, not an accent, and where it is required, it is always required. For example, maw' means "be crazy" but maw means "offend." If you wrote maw'a' tlhInganpu' you would be asking if Klingons offend.
The problem is that Duolingo, which wants to be generous about punctuation, thinks qaghwI' is mere punctuation, so it's very difficult to get Duo to enforce correct spelling. You will have to do that yourself.
If you're on an iPhone, it's very difficult to get the phone to stop autocorrecting the qaghwI' away as you type. Use a computer if you can, and that way you have access to the tips and notes section, too.