Setup your default configuration items.
Open-AudIT Default Configuration Values and Description
Make sure if you wish to use Discovery, you have default values for default_* items.
Audit
...
a single Windows computer
...
.
https://community.opmantek.com/display/OA/How+to+audit+a+single+Windows+computer
Try using Open-AudIT to discover
Discover a subnet.
https://community.opmantek.com/display/OA/How+To+-+Use+Open-AudIT+Discovery+on+a+Subnet
Or use Open-AudIT to discover your entire
Discover your Active Directory
...
domain.
How to use Open-AudIT Discovery on an Active Directory Domain