Dreamhost, Ruby on Rails, attachment_fu and RMagick

Dear Forum,

I am hosting a Ruby on Rails site on Dreamhost and use attachment_fu
and RMagick to upload images to the site.

Everything works fine on my development machine. However, on Dreamhost
it appears to be failing silently. Is there some additional
configuration I need to get this to work on Dreamhost?

In my Apache access log I was able to find the following:

[10/May/2008:11:27:42 -0700] "POST /assettype_images
HTTP/1.1" 301 601 "http://www.nnnnnnnn.com/assettype_images/new"
"Mozilla/5.0 (Macintosh; U; Intel Mac OS X; en-US; rv:
Gecko/20080404 Firefox/"

So the POST went to the "new" action on the assettype_images
controller. Which is correct. But the image never gets uploaded. I
have been using JPEG images of around 150k in size.

I'm puzzled. Can anyone please help me.

Thanks in advance.

Kind Regards