I have had a similar issue in the past. After reviewing your site, I see that you are using drop down menus at the top of your home page. Search engine crawlers do not read these links so they will not be included in the sitemap. Also, if you are using javascript, for example if you are having a link open in a pop up window, crawlers will not read these links either.
What I had to do was create text links for the pages I had in the drop down menus. As soon as this happened, the XML sitemap read all of the URL's.
An example:
www.local-shoppers.com : The drop down menu for the Browse by City feature contains links to 20+ URL's however, XML Sitemap did not pick them up. I had to create the text links for those URL's to be included, which are now found on the left hand side of the page.
I hope this helps
Mike
www.local-shoppers.com