COM client in C++ AND COM server in C#

[n4nature]

Below is the code for COM Client in C++, which calls COM server written in C# below. I have copied an interface.

This is more of a C# question. But I am guessing most of you would know about it.

COM server interface in C#

[Guid("4df99b70-e148-4432-b004-4c9eeb535a5e")]
    public interface IFunctionDiscovery
    {
        unsafe void GetInstanceCollection(string pszCategory, string pszSubCategory, int fIncludeAllSubCategories, CFunctionInstanceCollection** ppCFunctionInstanceCollection);

    };
    public class SampleClass : IFunctionDiscovery
    {
        public unsafe void GetInstanceCollection(string pszCategory, string pszSubCategory, int fIncludeAllSubCategories, CFunctionInstanceCollection** ppCFunctionInstanceCollection)
        {
            System.Console.WriteLine("GetInstanceCollection() called...");
            CFunctionInstanceCollection* ppFIC = new CFunctionInstanceCollection();
            ppCFunctionInstanceCollection = &ppFIC;
        }
    }

Compiling the C# code, gives an error:

Program.cs(19,21): error CS0208: Cannot take the address of, get the size of, or
declare a pointer to a managed type

Compiler is pointing at the last argument in GetInstanceCollection method of COM server. Does anyone know how to fix the problem?

Thanks!