XslCompiledTransform and Com+ dll

i have Com+ dll written in c++.

i am using one of it's properties (taken from ole viewer since i don't have the source)

[id(0x00000002), propget, helpstring("property getguid")]
HRESULT unique_id([out, retval] BSTR* pVal);

the property is called inside xsl.

when i use it with MSXML2 (http://www.microsoft.com/en-us/download/details.aspx?id=19662)

it work's.

when i try to use it in C# with XslCompiledTransform by adding the dll as

XsltArgumentList argList = new XsltArgumentList();
argList.AddExtensionObject("http://www.mydomain.com/mydll",Activator.CreateInstance(Type.GetTypeFromProgID("mydll.Class1")));

i get error:

Additional information: Extension object 'http://www.mydomain.com/mydll' does not contain a matching 'getguid' method that has 0 parameter(s).

the same problem occurs as well with method's and not only properties.

as there any other way to work with com+ dll?