Smoke simulation problem

I am trying to build the explosion (see: http://www.blenderguru.com/how-to-create-an-explosion/ )

Vista W32 SVN 33568

I succeeded once to render smoke to an AVI, but now not anymore? And I do not know what made it work.
I see it in the 3DView ??!!!
What do I miss.

Furthermore an observation: Ward suggests to let the particles start and stop at frame 2,
but that does not work? Changing back to 1 and 1, it looks like the tutorial??!!

EDIT:
Solved … follow the tutorial more exatly! (observation stays)