I would ask both of you the same question, and then give you both the same suggestion. Has your airprint printer ever worked yet with the pad? If it used to, and now doesn't then i am not sure what to suggest. If they are both new, then i will suggest the standard approach (at least for the hp, and may be the same for the canon).
From the control panel on the printer, look around for the control that will check online for a printer firmware update, and have the printer get it and install it. Then reboot the printer. I know that many of the hp printers did not ship with current airprint stuff, and needed to be updated before they would work. (mine included).
For the hp printers, they are very specific about doing this step from the printer while it is on line on the wireless network, not from the spftware loaded on the computer.
The hp airprint stuff is very reliable. Once i got mine updated, it works like a charm every time, for almost a year. I think once you get your going, you will have the same results.
As respects the canon... I have not used one, but i would be the same sort of update is probably needed. Check your books, it probably walks you through a firmware update in there some where.