okay, looks like niclarossini.com was approved, so let me share my experience with those who are banging their heads:
1- if the validator can’t fetch the url permanently, you didn’t give the root url, and the robots.txt file is in good order, you may have a problem of hosting IP being blocked by Twitter. If you’re on a shared server, this may be a common issue. Get a dedicated IP or move somewhere else.
2- the correct tags to use are those listed on the card summary when you visit to apply. So it’s
twitter:image:src and NOT
tags for the summary card:
Should you see another format, avoid using it because the card doesn’t validate.
IMPORTANT: never give the root to the validator! If you give the root, it won’t be able to fetch your url. If you put the tags in your index page, fetch http://yourwebsite.com/index.php or .html or whatever
Do NOT add a trailing slash at the end of your domain in the tag or the validation fails.
When submitting your card, give the same description you use in the metatags.
I hope this helps, and it’s valid as of November 20 2013.