A few points to check:
- Did you remember to select ALDIKO as the compatibility mode? I personally do not know exactly what it does but it is probably needed.
- If you try and use the HTML version of the catalogs do you see the download links? Since the HTML pages are generated from the XML ones that can act as an easy check on what is in the XML ones.
If you cannot spot anything yourself, then it might be worth grabbing the log file (as described
here in the documentation). FYI we have added an option to the Help menu in calibre2opds for the next release to make it easier to view the log file). If you want to post the contents of the log file here (wrap it in code tags to keep the post cleaner) then I can see if I spot anything strange in the settings being used.