Adobe plugin fails to find PDF specified in XDP sent to browser

Question

We have a private website that sends XDP files to the browser.  These XDP files specify PDF forms on our server.  For some of these XDP files, the browser reports something like this:
The file you are attempting to open contains comments or form data that are supposed to be placed on ObservationRequest_PrimaryToddler.1e.pdf. This document cannot be found.  It may have been moved, or deleted. Would you like to browse to attempt to locate this document?
If the user responds Yes, and navigates to the form, it works as expected.
If I look at the generated XDP file, and copy/paste the PDF location into a browser address bar, it is able to find it.
This one fails:
<pdf href="https://myWebSite/Forms/ObservationRequest_PrimaryToddler.1e.pdf" xmlns="http://ns.adobe.com/xdp/pdf/"/>
This one works:
<pdf href="https://myWebSite/Forms/StudentReg2014x.pdf" xmlns="http://ns.adobe.com/xdp/pdf/"/>
I've tried specifying myWebSite in the Trust Manager and in Security (Enhanced) in the Adobe Reader->Edit->Preferences. I've also tried turning off Enhanced Security. I still get the message. Why is this happening?
The browser is either Chrome (version 37.0.2062.103 m) or Firefox (version 29.0.1).
Adobe Reader is version 11.0.08.  The plug in version is 11.0.8.4 (11.0.8 for Firefox).

Answer 1

Well, I found the problem.
The PHP script that generates the XDP sends it to the browser and writes it to a file.  Unfortunately, the version sent to the browser was different than the version written to the browser. Specifically, this was sent to the browser:
<pdf href=\"c:/data/websites/private/Forms/ObservationRequest_PrimaryToddler.1e.pdf" xmlns="http://ns.adobe.com/xdp/pdf/"/>
And at the same time, this was written to the file:
<pdf href="https://myWebSite/Forms/ObservationRequest_PrimaryToddler.1e.pdf" xmlns="http://ns.adobe.com/xdp/pdf/"/>
This was a change made for testing from the server that never got reverted.