How do you know if you take a penalty in Yahoo?

[sumitkhare]

I lost my rankings, keywords and everything on yahoo in the past three months. I'm still in Google and MSN, so how do I find out what caused this disappearance in Yahoo? I did seem to take a penalty in Google in June but after a month and a resubmission request things went back to normal, are google and yahoo linked?
Is there somewhere to contact to find out if there has been a penalty issued?
Thank you