trackback problem

hello

my trackback and pingback is not working on version 2.0.4.
I can pingback my own articles, but as soon as pings comes or goes to other blogs, no trackback or pingback are working. I checked all settings, but there it looks ok. I also had this problem on version 2.01, but now I like to fix it. Could it be also some provider setting and if which?
Thanks