Try

? oReg.ReadRegistryString(HKEY_CLASSES_ROOT, cClassId, "")

>I have the following code
>
>

>
>#DEFINE HKEY_CLASSES_ROOT -2147483648
>
>CLEAR
>
>SET PROCEDURE TO Registry.prg
>oReg = CREATEOBJECT('registry')
>
>oDll = CREATEOBJECT("MyDll.MyClass")
>cClassId = COMCLASSINFO(oDll, 4)
>cClassId = "CLSID\" + cClassId + "\InProcServer32"
>
>? oReg.ReadRegistryString(HKEY_CLASSES_ROOT, cClassId, "Default")
>? oReg.ReadRegistryString(HKEY_CLASSES_ROOT, cClassId, "ThreadingModel")
>
>RETURN
>

>
>In the registry, the default value contains the full path and name of
>my DLL, which is what I want.
>
>In the 2 calls to ReadRegistryString above, the ThreadingModel is returned
>fine, but with the default key, I get NULL returned. Is there some way of
>acessing the Default key?