issues with integrating third party search engine

hi,

I have two issues.

1. my integration with Stellent verity search engine is working for the first time, but when I search again, nothing return, even on the same search criteria. I wonder something wrong with session object, please explain how session, rawsession object works related to getSearchResult(). session object is returned instead rawsession in executeQueryWithSession(), even though rawSearchResult has been set on rawSession.

2. it is very slow for the search result to return, though all the URL are valid. any way to improve the speed?

thanks!

T.J.