Heart of Nightmares Scenario Question

Team

I have beaten everyone, taken all castles, own all mines etc beat the "Spirit of the Water Dragon" which was fairly easy but now I'm stuck. :(
I don't know if its a bug, or I am missing something.

I've found a not working subterranean gate but cannot find out how to activate it - if it is possible, or there to trick you or a bug.

The Quests left are
Yume's waterlily to open the way to the temple of endless springs - but I can't find anything..
Find Mother Namtaru
Gain her trust

I cant do anything.
Any assistance?

Thanks


PS... everything else works for me fine
Win 7 64bit
loads of ram
good vid card
HOMM6 with latest patch