Duolingo usually completely ignores the capitalization (which is a problem since Klingon has an unusual pattern of capitals). I do see a report from a listening exercise, that I assume is yours. It looks like there was also an extra space at the end, but I wouldn't think that would cause it to be rejected either. I also cannot see any other reasons why it would have been rejected. I'll see if I can get a programmer to look into it.
Wait a moment. If it was a listening exercise, then you should have been typing the Klingon you were hearing, not translating it. So if that homophone report is from you, then you typed in the wrong language. If that was not your report, then I will need a screen shot to have any idea what went wrong.