Yahoo tracking domain, disregarding sub-domain

Yahoo is tracking my domain but it has completely ignored my sub-domains

[DjSonic]

Hi,

Problem I am facing is - I have a page rank 6 site and it's 6 months old now.

It running on 1 domain and 2 sub-domains.

It's soaring in google in terms of page rank and pages indexed - i.e. google likes both for the domain and the sub-domains.

Yahoo on the other hand - only has homepage indexed. None of the sub-domains are indexed.

1. webmaster tools are installed (google,yahoo,msn)
2. sitemaps are configured in robots.txt and submitted thru webmaster tools as well.

What am I missing...?