CSV file exported with HTML from page and not data

I'm using the 3.x dev version of Views Data Export along with Views 3.7 for Drupal 7 (7.19) and followed the documentation exactly. However, upon export of any type of file, it's filled with the HTML of the page but no fields exported. Upon looking through the code exported, I realized that it exported the file with the full HTML of a 'page not found' error (see attached).

Upon looking at the system log, there is a 'Page not found' error for the path specified in the Data export config immediately followed by another log entry with this:

Warning: Cannot modify header information - headers already sent by (output started at /var/www/html/i6/includes/common.inc:2681) in drupal_send_headers() (line 1232 of /var/www/html/i6/includes/bootstrap.inc).

Any ideas?

Thanks.