fbml and dreamhost

help me....please...
I'm trying to set up just a simple "getting started" application with
dreamhost on facebook.
I'm having two problems:

1. the rails application works fine until I install the rfacebook
plugin (just installing it and nothing more) and then all I get is a
HTTP 500 error...once I delete the plugin everything goes back to
being fine...
The only solution I found to a similar problem is to just move to
another hosting company...

2. while the application works fine on facebook using iframes once I
switch to FBML I get a HTTP 422 error...
when I look at the application not through facebook it looks
absolutely fine (of course the FBML tags are not rendered but
everything else is completely normal). the problem stays the same even
when there are no fbmls tags at all !
I stumbled across a post which claimed that theres a problem with
rails newer versions fbml compatibility but id like to assume its not
very likely...

please...help me....
Thnx...