There are a few different scenarios for how you may be using Reader Extensions and Reader. Let me lay them out and a bit of what may be happening in each case. Then tell me which case is yours and we can go deeper.
- The form is a dynamic XFA form: Annotations, even file attachment annotations, are not possible on dynamic forms. If you want to do attachments, then you need to use what was called embedded data objects back in 7.0.
- You are opening the form in a browser and submitting from there: Annotations are not allowed in the browser unless it is hooked up to a review server (in other words, the annotations do not go back with the form data). There are a few tricks around this, but browser-based review has been deprecated in A9 and X. http://acrobatusers.com/forum/collaboration-commenting/browser-and-shared-reviews-readers might be of help to you as well. You would also need to have a reader extensions credential that provides this right. It was an extra cost option in the 7.0 timeframe, but more recent credentials (try the current trial credential... I can tell you the URL if you have trouble on the trial page) will work with older servers... you may want to test this and/or wait for my special hints BUT this scheme is on its way towards obsolescence,
- You are using embedded data objects and have reader-extended the file with the embedded object rights (EFModify): This should be working. Note that you would need a tool like assembler to extract the data objects on the server: this was licensed separately in the 7.0 timeframe.
So you are a combination of cases 1 and 3. There is good information out there to point you in the right direction.
Thom Parker, one of the Acrobat experts, did a great tutorial on this on Acrobatusers.com .
So watch this and then just make sure that the form has been reader-extended for Embedded File Attachments.
And be warned that we have layered on functionality in each release and rebranded. So what we started as the geeky "embedded data objects" became "PDF packages" and then had Flash added and is "PDF portfolios." But embedded data objeects are still in there as the lizard brain, and work back to 7.