variant args to COM

Hello
     This weekend marked my first experiece with COM, I'm wrapping a SOAP
library and everything has been going well until I came to one
particular function. The COM Interface Browser gives the following
signature;

name - com::bstr
val - com:variant
namespace - com::bstr
type - com::bstr
type-namespace - com::bstr

     Now, with all previous functions I can just pass a string to the
com::bstr arguments but i can't find an indication of what to pass to
the com:variant. I've tried a string and a string wrapped with
(make-lisp-variant :bstr a-string) but both give a 'cannot be converted
to foreign type (:STRUCT COM::TAG-VARIANT)' error. Can someone indicate
where I'm going wrong?

     thanks

         Andrew