Confirm the missing file precisely
If an organizer writes “Please return the attached form by Wednesday,” look for the form that day. Ask for a fresh copy if it is missing. Keep the deadline in the task and mark the form as a dependency so the missing file stays visible. If there is an attachment, open it and check the event name, year and revision. A form with the right logo but an old deadline can look convincing at first glance.
Ask for exactly what is missing
A short request works: “We received the June trip email. The only attachment is the schedule. Please send the consent form due Wednesday.” This tells the organizer which message to fix and reduces the chance that they resend the same wrong file. Do not assume an extension unless they give one.
Make the dependency visible
Keep two separate states: waiting for the correct form, then completing and returning it. Give the first state an owner and a follow-up time before the deadline. When the form arrives, check whether the organizer changed the deadline or return route before completing it.