Note that the second letter in yIjatlh is a capital i. In the Skill which includes this exercise we have not yet introduced the imperative so we don't expect it to be used. Also note that there is no punctuation which means we are looking for the definition, not a conjugated sentence. However, because someone might already know the imperative prefixes and not notice the absence of punctuation, we do accept yIjatlh as an answer. If you tried it and were marked wrong, it was probably because you used a lowercase L instead of an uppercase i.