CANNOT buy photo book from Aperture 3.3.1

Exactly what I have experienced (ordering prints). Problem has been there since 2010 when I encountered it the first time. I have to break my photos into chunks (may be 60 MB, typically on the order of 60-80 picture) to get it to complete without giving network failure. Two years later, same problem (just tried an order for Christmas with same problem). Well, they are probably busy fixing the complicated April '13 bug in Calendar.

Edit: Forgot to mention that the solution for me is to load the Aperture library in iPhoto and order from there. Good deal for Apple, as prints there are more expensive. I guess it costs extra to get it working? Amazing that the "pro" app only works when supported by iPhoto.

Finally got there thanks to previous posts! Changed Apple id password to include more numbers and changed all answers to security questions to at least 6 characters.

I have an update to this problem. You will also receive this error if you have 2-factor Authentication enabled on your Apple ID. This is a new system Apple implemented recently which sends a code via SMS or notification to any designated phone or iPhone you configure. This code is required in order to access your iCloud account. E.g. when you sign into appleid.apple.com, it will ask you which of your configured numbers you wish to send the code to (in my case, I would pick my iPhone) - a code then appears on my iPhone screen, and after entering that code on the web page, I'm allowed in.

Anyway, Aperture doesn't support 2-factor auth yet, so I was reaching the Shipping Address page and getting that stupid "Please try again later" error. I eventually went to appleid.apple.com, disabled 2-factor authentication, entered some security questions/answers, and went back to Aperture and it's now taken me to the "select prints" page, which is further than I was getting before!

Also, just a side note: with security questions, I don't think it's a very good idea to enter the real answers. E.g. if your childhood nick name was "chuck", that's NOT a secure security question, because lots of people besides you know the answer. You're better to put in totally random answers. E.g. "what was your favourite elementary school teacher?" answer: "lightbulb" (or whatever). Just a thought.