Rails post request got 301 redirect to get

Guys I’m a new to dreamhost RoR.
I just followed the instruction on how to build a RoR project on dreamhost with passenger. Everything looks fine until I tried to submit some data via POST method. From the apache access log, I can see that all the POST request were 301 redirected to GET request and all data was lost.

[quote] - - [27/Sep/2011:07:58:40 -0700] “POST /votes HTTP/1.1” 301 496 “http://apps.weibo.com/votethem” "Mozilla/5.0 (Windows NT 5.1; rv:6.0.2) Gecko/20100101 Firefox/6.0.2" - - [27/Sep/2011:07:58:40 -0700] “GET /votes HTTP/1.1” 500 738 “http://apps.weibo.com/votethem” “Mozilla/5.0 (Windows NT 5.1; rv:6.0.2) Gecko/20100101 Firefox/6.0.2”[/quote]

I didn’t change any config files except the database.yml which I don’t think can trigger the redirect. Could anybody tell me why is this happenning?

Many many thanks!