Calander Sharing Permission is not effective between Exchange 2007 & Exchange 2013 User

When a Exchange 2013 mailbox user share a calander with user in Exchange 2007 with OWNER permission, but Exchange 2007 user cannot modify or view full details of Exchange 2013 user calander.

And same behavior from Exch2007 user sharing calander with Exch2013 user.

In both scnarioes we can view only free/busy information. Cannot see full details of the meetings, cannot edit/modify. But permissions are set correctly.

Getting Yes or No prompt window with message "You dont have permission to view the calander, Do you want to as User A to share his or her calander with you?"

We are in Co exsistance with Exch2007 and Exch2013 CU3.