Translation:It is set up to depart.
Remember that the software is not smart enough to show you just exactly your mistake. We have set one "Best Answer" and that one best answer may have 4 or 5 differences from your sentence that are not actually wrong, just different choices. But somewhere in that sentence is an actual error. "Ready to leave" is accepted in many variations of the sentence. I would need to see your full entry to find what caused it to be rejected, whether it is your error or ours. I do not see a "my answer should be accepted" report that I can check. Do you have a screen cap? Or can you at least type the whole sentence you entered and hopefully, if you actually had an error, you will repeat it.