Thanks for the extended help sofar, in mean time I tried to work around this issue with 'reg query', but that gives different results running from CLI or batch/within Perl :(

Q: what do you mean with The used flags have little different background?

A: These were suggested with searching a different part of the registry with a different question

Q:Also note that Here I didn't get undef values, but empty results is not so true: if you put null values as hashref's keys and then you look for the number of keys, ie zero.

A: Well in this case I got a hasvalue returned, in the other case an undef value. Maybe that is similar, I thought that was different

Will check this KEY_READ() solution, in the previous node. UPDATE! The KEY_READ() worked in the previous node. So that gives a good feeling.

Anyway, no matter which access methode I use I get '0' results. Is there a way to switch on debuglevel to full so there is more data to work with