I keep getting this error after creating and then viewing a webform report node. Thing is, there is no "Report Criteria" item to be found anywhere on the edit screen or anywhere else I have looked. Unlike others who have had a similar problems (e.g. http://drupal.org/node/1117394), the webform_report table is in the database, and records are being added to it. Here are some other symptoms:

* The newly created nodes do not appear in the default Content view (/admin/content) or in the general site feed (/node), even though there are node records created in node and node_revisions.

* /admin/content/webform_report produces a white screen.

The site in question is using Drupal 6.22.

Any ideas?