When you are using the filled out form filter and add the web page criteria, do you take out the http:// ? Marketo doesn't seem to want that prefix. See if that works.
Thanks for your response. It was actually because we had the wrong munchkin code, so it wasn't grabbing any of our pages. I guess we need separate munchkin codes for our wordpress-hosted pages v. our standalone pages that we upload via FTP.
If you are using WordPress for your site, there is a WP Form plug-in that integrates with Marketo. I have been using it since the start of the year and it reliably triggers Marketo Smart Campaigns and passes through all fields, hidden fields and munckin info (Inferred Country, etc.):