This was mentioned on the list a log time ago IIRC. The trick
was that you cannot discover Improved Opium Production until
after you fully know Opium Production. Finish learning the
Opium Production skill, and then try researching again.
-- Please use bron-oly2@bronze.corp.sgi.com for Oly2 correspondence. Use bron@sgi.com only if you require fast response. These statements are my own, not those of Silicon Graphics.