form_item()

I had tried to get diff to work a few weeks ago, and am now trying again.

I get a list of revisions, but when I select one (i.e. diff to: previous), I get the following error message:

Fatal error: Call to undefined function: form_item() in /home/mysite/public_html/rendez/sites/default/modules/diff/diff.module on line 84

(I've edited to insert "mysite", as I'm using a pointed directory under Fantastico on site5.com . I believe that the directory structure should be correct, so there's something about "form_item() that isn't right).

I'm running Drupal v4.74 . Any suggestions? Thanks.