Just tried to add my Velocity number to an existing ANA booking. Velocity now appears in the list but I get an error message:
We were unable to verify your mileage number.
If you have recently registered as a new member, it may take some time for your registration to be processed, so please try again tomorrow or at a later date.
I wonder if it is because their system merges first and middle names so the record doesn't match Velocity's, but I doubt it is that sophisticated. May just have to get it added at the airport.