yahoo messenger app not working. pls help

[shin_pen]

i got the iphone around 2 months ago and the app works fine. now I can't log in anymore. it always says "sign-in problem. the request timed out.. please try again". same goes for my sister's iphone 3gs. the other internet apps work fine, like facebook or twitter.

already tried reinstalling it from the appstore, and resetting. still nothing happned. please help.

thanks!