Hi SUR-PTR the problem is that Queries are WQL and Reports are SQL so you basically need to convert the WQL to SQL. For instance you'll find that SMS_R_System view doesn't exist in the Report SQL Properties, rather v_R_System.
You will also need to check that the custom registry is being captured to the SCCM Database otherwise you're not going to be able to query for it. This is usually done using custom mof files.
http://scug.be/blogs/sccm/archive/2008/08/29/sccm-customizing-the-hardware-inventory-to-report-a-custom-registry-file.aspxSorry couldn't be of more service.
Cheers