importing error message

I am trying to import my old blog contents from wordpress.com to my new wordpress.org blog. My new site is http://www.thehealthyhostess.com and my old site is http://www.healthyhostess.wordpress.com. The export/import feature lets the posts up to July 09 be imported to my new site, but it is missing the posts from July 09 to Dec.09. When I import the wordpress file it says there is an error. It says there may be more information with the server. Can you PLEASE help me?! I don’t know who I need to contact or why the problem is occurring and I am missing all of my stuff!
Thanks!