show smf recent posts with rss widget ?

hi,
i searched lots of thing. but it is too complicated.
easly, i will want to show my smf forum’s rss in sidebar by using rss feed widget.

but,there s a problem. wordpress rss widget is not updating the last posts. i see older posts. example; in smf forum, users replying to 5 or 10 different topic , but at wordpress sidebar i can not see these new recent post.

How can i fix that?

Thanx for your help.