How to clear the Facebook cache – DEBUG tool
Sometimes a post that you are creating, doesn’t suite your needs. You want to change, for example, a picture that will stronger attract viewers attention. You change the source site, paste the URL for the second time and nothing changes… That’s because parsed page elements are stored in the cache. When you are adding a post to your facebook page, when the URL is paste for the first time, it is being cached in the facebook cache. Facebook provides a way of dealing with this problem. All you need to do is clear the cache. Visit http://developers.facebook.com/tools/debug, paste the URL to the object that you want to post and click
Debug. Now try adding a post once again. You will see the changes made.