Q: Cannot wifi print.

I had a similar problem with my Canon printer.  It stopped wirelessly connecting to my MBA but did connect wirelessly to our MacBook.  I turned it and my MBA off, waited, turned them back on and it did not fix the problem.  Then we had some electrical work done on the house and the power was out for 15 minutes.  That fixed it!  So the first action I suggest is you unplug it, unplug your Time Capsule, shutdown your Mac, wait a minute or more and then plug them in again.

In addition, I found it useful to install the software form the CD provided with the printer rather than downloading the drivers.  The download options were confusing with different drivers for different functions and the scanner did not work from the System Preferences > Print & Scan menu until I installed the software from the CD.

If all else fails contact Canon.

http://www.canon.co.uk/Support/Consumer_Products/Telephone_Numbers/telephone_num bers.aspx

Also check that your MBA is on the same network as your iPad.  That will confirm your MBA is on the correct network.

I found some useful Max OS X printer references in another thread:

http://support.apple.com/kb/HT4670

http://support.apple.com/kb/HT3771