Sharing URL On Facebook using Addthis

Sharing URL On Facebook using Addthis

we have a news website and using AddThis plugin to share news on Facebook
, sometimes when we try to share news on Facebook it doesn't detect the
page info (title ,desc , image ) and when we put the same URL on Facebook
debugger every thing running correctly and page info detected , and when
return to the web site and use the same URL we can share it normally .
the web site created using asp.net 4.0 + SQL server 2008 + iis 6 and the
website behind a firewall
thanks