Problem with file uploads

I'm trying to write a simple file upload form. The upload form is a view like this:

<%= start_form_tag( { :action=>'upload' }, :multipart => true) %> <p>Upload File: </p> <%= file_field('upfile', 'data') %> <%= submit_tag('Upload') %> <%= end_form_tag %>

The controller has upload defined, and there is an upload.rhtml file in the correct spot. However Post attempts to the upload action fail with a 404 error. The strange thing is, GET works perfectly fine (the 500 error is due to a list in the upload view being undefined due to the lack of expected POST data). Here are the results of a submission of my form, followed by the results of a direct browser access.

"POST /connect/upload HTTP/1.1" 404 291 "GET /connect/upload HTTP/1.1" 500 7688

Anyone have any ideas why this may be happening? I'm using rails 1.1.6 with Ruby 1.8.4, on a CENTOS 4.3 (Fedora Clone) box.