Yahoo Bot, where are you?

Hello, my site is ElForro [spanish community]

The Google Bot crawls about 10.000 pages a day in my site, but Yahoo does it for only 200/300. And when I search "site:elforro.com.ar" in Yahoo, there are only 20.000 results, while in Google I've got +100.000 using the "site:elforro.com.ar" query that I know it's not accurate, but at least gives me an idea... Yahoo is having a problem with my site?
By the way, in the "Sitemaps Download Log", Yahoo appears to be downloading my sitemap_index once a day... I've added the URL to my robots.txt now, to see if something changes...

Any advice? Thanks!

Edit: Is this matter of good luck or something like that? Because Google spends all day in my forums, crawling 20/30k pages... Now Yahoo started to crawl 2/3k per day too... But I can't notice any change in organic visits, or number of pages indexed... since months... I must definetly be doing something wrong... If someone can give me some advice, my forum is at the top of the message...

PS: Sorry for my poor english