EMPTY sitmap for DUMMIES

Dear all,
I have read the threads

Big, Over-Arching Sitemap Architecture Discussion (tm)
The site map is not being populated
Cron limit defaults to 0 and as a result no old content is added to sitemap

but I have not got any information which helps me as an user of Drupal v6x and XML-Sitemap to solve my 'empty sitemap' problem.
This problem poped up newly with 29.4.09 release (all previous releases have been applied).

Please consider the following:
There is users out in the space who are using Drupal v6x and XML-Sitemap on production sites. And as I have the feeling this is not only a view ones.

So, they are upgrading on a regulary base to new dev versions. And suddenly xml sitemap isn't working any more.

Google begins to moan on this and as a matter of fact site hits are dropping. So, users try to get a short and simple 'How to' on how to fill their xml sitemaps once again.

But currently I do not have a chance to fix this - yes - I can't even get the status of is this. Is it a but or is it a feature?

So, please, would somebody come up with a short and simple explanation of what people should do, when XML-Sitemap keeps empty?

Many, many thanks in advance

Martin