/RANU switch on RegPkg.exe always fails on VS2010 SDK

Question

Hi;

I am trying to get RegPkg to register a Visual Studio 2010 extension package under HKCU rather than HKLM. Supposedly, the /RANU switch is for that (/? help lists the switch), but if I invoke "RegPkg.exe /RANU assemblyToRegister.DLL", RegPkg fails with "regpkg : error : Invalid Parameter 'RANU'"

Tried various other placements and casings with no effect. Invoking RegPkg without works, but the package is imported to HKLM. Any clues?

Thanks in advance.