Do you mean you don't see the links when looking up your site in Yahoo Site Explorer? If you can be a little more specific, we can probably lend a hand.

Ya not clear. Could you elaborate more on that

Yahoo site explorer is not an accurate source of backlink data. What is the URL and I will check for you.

you can ping those links all day that does not guarantee that yahoo will pick it up or that Google will add it to yoursite. All so if the links are just comments on a EDU blog Google see them as low quality because Google know about comment spam

many times backlinks will not show up immediately or be picked up right away a steady strategy of continually building backlinks is reccommended. If you want a free backlink check it out here ODLinks » | EXTREME WEALTH MECHANISM

It sounds like these backlinks were created just a few days ago, it can take weeks for links to be indexed, even if pinged. Just be patient; if you know it's there it will get crawled and indexed eventually.