I've never had any luck with getting the Aperture to PBase export plug in work. Images don't post at all. I'm using the latest versions of Aperture and the plug-in.
If anyone has been, or is currently getting this to work properly, I would love to get in touch with you and ask you a couple of Q's.
BTW - I've tried out the Aperture to Picasa export and it works perfectly.
Thanks