Using Pages '09 v4.2 on latest Mountain Lion update (10.8.2 + supplement).
Opened new Pages document. Typed some gibberish. Then from Share > Send via Mail > Pages, this resulted in an iconified Pages document attached to a new email.
So it works for me. The gibberish that I typed: “foobar ex libris.”
I would restrict filenaming to all ascii or ascii punctuated with these characters: ‘-’, or ‘_’
Anything else with embedded spaces, or other embellishments may be your cause.
I just ran a test with Pages again here. Chose the Send via Mail > Word option and it dutifully placed a Word document into Mail as an attachment. I then selected that attachment, hit the space-bar, and QuickLook opened the Word attachment in LibreOffice Writer, something I optionally installed in place of MS Word.
I have just systematically reviewed my Pages preferences and Inspector settings and see nothing that alleviates my consternation for your results.
My Pages '09 v4.2 was purchased from the App Store.
Jerry asked the name of your file in the other thread and I don't think you responded.
I'm still using Snow Leopard, so I can't check, but I believe Export fails silently, just as you are describing, in the newer operating systems, when the name contains an "illegal" character. Previously the system was apparently more tolerant.