Getting error while facebook.fetchObject function.

Hi
I am using following spring social 1.1 function of facebook

facebook.fetchObject("482847971787545/feed", Post.class);

where "482847971787545" is my page id and i am getting following error
org.springframework.http.converter.HttpMessageNotR eadableException: Could not read JSON: Unexpected token (END_OBJECT), expected FIELD_NAME: missing property 'postType' that is to contain type id (for class org.springframework.social.facebook.api.Post)
what can be the issue.
Thanks