First Omeka 2.1.3 installation / retrieving error messages

I've got stuck with a first-time Omeka 2.1.3 installation (http://omeka.org/codex/Installation). I've followed steps 1-5. At step 6 I get the message 'Omeka has encountered an error'.

I can't get Retrieving Error Messages to work despite having edited the .htaccess file as instructed and have been unable to Activate Error Logging.

If these instructions don't work, is there another way to retrieve error messages so I can see what the problem could be with the installation?

If you've set log.errors to true in config.ini, I'd double check that the application/logs/errors.log file is there and writable by the server (you might have to copy errors.log.empty to errors.log).

It's also worth double-checking the database information you put in db.ini