"Next (Options)" button reloads first page

Node import was working perfectly for me, but I recently upgraded to drupal 5.14 and now for some reason it's not working. I get as far as the mapping step, then when I click the "Next (Options)" button it reloads the first page instead of proceeding to the options page.

I found a post on the drupal forum for this issue for which there was a patch, but it was from 2007 so I wasn't sure if it would apply: http://drupal.org/node/112173 posts #60-62.

Thanks!