I wasted more time that I want to admit do trying to figure this out. I was trying theme a specific CCK field named field_images on all the nodes where it appears. The devel_themer module was listing content-field-field_images.tpl.php as a candidate:

But after copying CCK's content-field.tpl.php into my theme and renaming it I couldn't seem to get the theme to pick it up. Roger López gave me the frustratingly simple answer on irc: "i think you need to have both templates in place"... duh. Copied content-field.tpl.php into my theme and everything worked great.
bug?
so, is this a bug? seems odd and confusing to have to "override" a file even though you're not making any changes to it. and when theming views this extra step isn't needed. what is it about cck that needs this base file to be copied over?
Common mistake
It's happened to me many times! Same principle applies to all templates. If the base one doesn't exist in the same directory, Drupal doesn't find the more specific ones.
Need to read from right to left
This is because the "Candidate template files" list need to be read from right to left, like HTML DOM CSS. The important thing is that exist the first template file (content-file.tpl.php).
not reading content-field tpl
Hi,
I'm having a problem I've been trying to fix in the previous 5 days but can't figure out how.
I created a new content type with cck, added a custom field, copied the content-field.tpl.php in my theme directory and changed it slightly in order to understand if it gets read or not, but the field in the form of the new content type creation is not created using the content-field at all.... even the Devel MOdule is not listing the content-field among the Candidate template files...
do you have any ideas why?
thank you
did you reset drupal's cache?
did you reset drupal's cache? I know it sounds obvious, but it often causes this problem.