Pidgin fails to block AIM contacts

Recently, pidgin has decided to stop blocking AIM contacts. Previously when I blocked a contact, I would appear offline to the blocked party, and the blocked party would appear offline to me. Now however, blocking a contact no longer works. multiple times I have been IMed by contacts who are supposedly blocked. Additionally, when I attempt to block contacts now, I get an error message saying the attempt failed.

"Could not add the buddy _________ for an unknown reason."

I ran pidgin in debug mode and it dumped this when I tried to block someone

(21:01:45) oscar: ssi: About to add a deny
(21:01:45) oscar: ssi: status is 0x0003 for a 0x0008 action with name no item
(21:01:45) oscar: ssi: Action 0x0008 was unsuccessful with error 0x0003
(21:01:50) util: Writing file blist.xml to directory /home/_____/.purple
(21:01:50) util: Writing file /home/_____/.purple/blist.xml

now not only does it refuse to add new contacts to the blocklist, but contacts that were previously blocked are now shown as online again.

Pidgin version: 2.4.1
Ubuntu 8.04 LTS
Kernel 2.6.24-25-generic
Gnome 2.22.3