Top Ranking in Google but Not on yahoo!

Hi,I rank high on google for some of my core keywords, but i am nowhere in it for yahoo at all. What issue might be related to this? Belows are my hypothesis,

1. it is because spammy sites link to my website, so I've got blocked from yahoo.

2. Cloaking / lifting copy?

3. Duplicate contents?

4. All of these

5. None of these

What would be the best possible answers to this?

Most important is ranking well in Google. I don't care for Yahoo or MSN rankings.

Yahoo and google have different algorithms so they provide different ranking for your site. Just focus more on on-page optimization because Yahoo gives more weigh on that.

good/quality backlinks are very important to google. keyword optimization on the pages and keywords in the domain is more important to yahoo. figure out which one you want more and focus on that. hope this helps

On page optimization really do weight in Y plus keyword oriented..on the recently update I think Y is most likely going now on the quality and quantity of links in ranking their on search result ..they are looking down to push authority/powerful sites as a factor on their rankings..

It is surely that yahoo is different from google .Yahoo is not as good as google ,I mean its security . I think it is because spammy sites link to your websites .