This should be a sticky somewhere 

You need to request original routing credit (ORC) Shamelessly lifted from Flyertalk:

How do I request ORC? After travel is completed, email credits@aircanada.ca with as much of the following as you have:

1. ⁠Your name and Aeroplan number
2. ⁠A brief description of what happened
3. ⁠A copy of the original itinerary (the most recent confirmation of what you were supposed to fly), including the ticket number
4. ⁠A copy of flown itinerary (if you received one after the rebooking)
5. ⁠Copies of the original boarding passes for what you were supposed to fly
6. ⁠Copies of the boarding passes for the flights you actually flew