Translation:That word does not appear on the list.
Your sentence is "Esa palabra no está en la lista." The verb in your sentence is estar. The verb in the Duolingo sentence is aparecer. Duolingo does not like students changing verbs and will almost always mark it wrong it you do so. Duolingo is trying to teach something specific, perhaps it is the introduction of the verb aparecer. Why fight it. learn it and move on.