roy’s posterous

Posterous Autopost Setup Problem

I'm running a custom blog engine on my website http://roytang.net, and I'm trying to get Posterous working to post there directly. I've already implemented RSD (the RSD file is at http://roytang.net/files/rsd.xml), and I already support Metaweblog API (I'm using it to post to my blog using Flock browser)

But when I try setting this up in posterous, I get the "unable to authenticate account" error. Any ideas?