Are are using WordPress 3.0? That is the only version that uses WP_DEBUG.
Are you using an old version of the plugin?
Yahoo requires an Application ID in order to ping them. Are you using a valid Application ID?
You might want to set WP_DEBUG to true in the wp-config.php file to see the rest of the messages.
If you can't resolve it, you should go to the WordPress forum for that plugin and see if anyone else is having the problem. if not, you can post the problem there.
Last edited by TopDogger; 30 June, 2010 at 20:09 PM.
"It's inexcusable for scientists to torture animals; let them make their experiments on journalists and politicians." -Henrik Ibsen