I have done some testing with this and I was able to get the same error when submitting the site map with Surveyor.
Digging around a little I found this page that describes why this error occurs:
It looks like it might be possible that the limit for API calls was exceeded for your ip address. You should try this again after the 24 hour period to see if you get the same error.
As for submitting the site map on the YSE please detail the steps you took here, and also let us know if you have an html or xml sitemap for your site.