Thanks, Ben, for that link to the Adobe file conversion table. According to my discussion with Adobe tech support, the newest version of Acrobat (Acrobat X Pro) and future versions will no longer support 3D file conversion. I didn’t get 100% clarity on that because the Adobe people seemed to be digging so hard for that info. Too bad, because I thought Adobe hit a homerun with the facility to display 3D models from multiple sources in Adobe Reader, which everybody and their brother uses.
You all might be interested in the article below from deelip.comanalyzing/criticizing Adobe for jettisoning their support for the 3D PDF format (at least from the creation side). The 3D PDF format is an ISO standard so it can easily be supported by other software vendors, but it's future is cloudy now that its biggest supporter Adobe has basically washed their hands of it.
I ran into this issue also, I put a post on the Adobe forum and they stated flay out that WF5 is not supported by 9 extended. My work around consisted of saving the model as neutral data and then creating the PDF from that, but for some reason it seemed to stop reading neutral data from me about a month ago. After that I started to use the iges file format. At the start of the New Year we upgrade to Acrobat X and got the Tetra 4D plug in. I would have to recommend upgrading to Acrobat X with Tetra 4D as it did not take long to recover the cost with not having to fight file formats every time.