Personally, I don’t have any experience relating with this issue, but due to may of my reader blog reported that whenever their Yahoo Messenger upgraded to the version 11.5, they noticed that the Emoticons seem to be not working. Whenever they try to send the Emoticons from Emoticons list, the emoticons didn’t appears. On the other hand, if someone send them a message with emoticons, it still worked.
If you face this kind of problem, please enter a comment with your current version of Operating System and also Hardware specifications. Just wanna know. Otherwise you can report directly to Yahoo about this via “Report a Problem to Yahoo” under “Help” Tab on Yahoo Messenger.
Solution: Try to upgrade your Yahoo Messenger to the newest version (currently for version of Yahoo Messenger 126.96.36.199)