AddThis

api.addthis.com under title

I have a static page with the addthis toolsbar that when shared with facebook works as expected e.g

************ Share Title
*thumbnail * www.mywebsite.com
* image *
* * Share description
************

However on a dynamic web page I do an ajax call to get the url, title, image and description to share and then construct the toolbar dynamically:
addthis.toolbox("#sharethis", dyn_addthis_config, dyn_addthis_share);
This is what I get:

************ Share Title
*thumbnail * api.addthis.com <---------- This should be www.mywebsite.com !
* image *
* * Share description
************

The dynamic web page shares the same url as the static page, so why is the subtitle different and what do I need to do to fix it?

Thanks