I have a category template from 3.3 and am testing 4.1. I keep getting this error, when saving a single new entry.

An error occurred publishing category '4': Publish error in template 'Category Archive': Error in <mt:Entries> tag: Error in <mt:DateHeader> tag: Error in <mt:EntryDate> tag: You used an MTEntryDate tag without a date context set up.

I reviewed the category template and it seemed fine with the EntryDate tage; publishing the main index publishes the new entry fine and nothing seems out of place on the site.

Any ideas about this error and what I can do to remove it? Thanks