i'm having trouble signing in to yahoo messenger i don't know what is wrong? could you help?

lisa grether, June 2011

What version do you use? The current version is ver. 11.0.0.2009.
There are often changes from version to version and those can make older versions uncompatible with the global servers.

Get the latest from http://messenger.yahoo.com/download/
(you can sellect your country to get a localised version)

Electro, July 2011