1) Your keywords on which you ranking are not targeted OR have very less searches in SE.
2) Yahoo Search send very less traffic because most of NET user use Google to search anything that why Google send traffic
Normally yahoo has low traffic value in search engine and if you are on top position with key words which are not search by people than you may not get traffic to your site.
We are in Top 5-10 on many Keywords in yahoo.com but not getting as much traffic.
Any IDEA?
muller if you are getting 15 to 25 percent of profit from yahoo then it good to my personal experience this is the best I got ever. rest is google google and google...............