I don't know … call me crazy now. I tried different things and every time after changing things i checked /var/etc/snmpd.conf. It's working now? Yesterday i made the screenshots and post the content of the config file. The essential lines were missing. This is what i did now:
First i just check and uncheck the boxes. Accordingly to the changes in the GUI the snmpd.conf was changed also. Then i tried to disabled completely SNMP services and save the settings. After that i enabled it again with checking the boxes. Works! Then the same but enabling without checking the boxes. Works too. Then checking the boxes ... works also.
It's not really nice not to know whats going wrong. But i can clearly say that i had this problem, not only on my machine. Since it's not a totally really needed essential feature (like IPSec), i accepted this behavior for a long time.
At the moment i hope, that it was a problem, that may be existed in older versions, and may be i upgraded it all the time, to the newer snapshots ... and the issue may only occur in touch with my existing config ... and it's now is away cause of the newer snapshot (wondering why i was yesterday not able to save the settings with same snapshot)?!
But thx very much for your help ... wishing you a relaxed weekend 8)