Supplementary question (with apologies to the OP): Why is it that this happens so often even with Air Canada flights?

I make sure the number goes on the file when I book. I make sure to show my card to the person when I check-in. Yet it seems to happen far too often that the points fail to show up, and when, as in a recent example, it's from Shanghai, the points cannot be claimed on-line.

So why does this happen so often?

Furthermore I'm about to mail in, but I can't find the boarding pass, although I have the original e-ticket and the baggage receipts with my name on it are stuck to them. I also made a points-qualifying duty free purchase in-flight (also not yet credited) and used an SSWU, which must presumably be noted somewhere. But without the boarding pass, am I going to be denied the points?

Peter N-H