This could have to do with the rate limiting for the number of requests being made out. While I'm not 100% certain how the search team rate limits a ping request with a sitemap, it seems to be consistent with hitting the upper bounds of the daily rate limits: http://developer.yahoo.com/search/rate.html
When you see this message, do you see it consistently for a 24 hour period?
I just got the limit exceeded error message after only one successful submit. The second ping fails. Has anybody solved this?
I get this problem too. I think there is a hard limit set per minute, because I have tried delaying my calls and it seems to work if I space them out. Also it seems that a certain number of calls within the same CURL session seems to trip the rate limiting.
Yes, there is a hard limit on the number of consecutive calls that are made in a short span. After hammering the service with 5 requests I believe it will start to limit you or space the requests out. If you manually space these requests that solves the problem.