Is curl enabled on your server?
This is one of those annoying errors because FB returns nothing of any use to help diagnose where the issue lies.
I have curl enabled and I am having the same problem.
Please provide the following information about your installation:
Wordbooker: 1.8.11
Wordbooker Schema: 8
WordPress: 3.0.1
PHP: 5.2.13
JSON Encode: PHP
JSON Decode: PHP
JSON Version: 1.2.1
SimpleXML library: PHP
HTTP Output Character Encoding: pass
Internal PHP Character Encoding: UTF-8
MySQL: 5.0.77
Database character_set_client : utf8
Database character_set_connection : utf8
Database character_set_database : utf8
Database character_set_filesystem : binary
Database character_set_results : utf8
Database character_set_server : latin1
Database character_set_system : utf8
Database character_sets_dir : /usr/share/mysql/charsets/
Database collation_connection : utf8_general_ci
Database collation_database : utf8_general_ci
Database collation_server : latin1_swedish_ci
Server : Apache/2
Active Plugins :
Bp Gallery ( 1.0 RC4 Update 4.1 )
jqZoom Plugin for Bp Gallery ( 1.0 )
BP Random Member Widget ( 1.0 )
BuddyPress Template Pack ( 1.0.2 )
BP Dev Sitewide Footer Content ( 1.0 )
BuddyPress Badge ( 1.3 )
BuddyPress Like ( 0.0.7 )
Buddypress Widget Pack ( 1.1 )
Bp Recent Profile Visitors ( )
Simple Page Widget ( 0.1 )
Can you try the version here:
http://www.pemmaquid.plus.com/wordbookerdebug181102.zip
it has a few more diagnostic checks in it