impossible read STGMEDIUM from RemoteGetData

[Pocholo]

i have created a dll with this idl file

//CustomMsHtml.idl
[
uuid(7522A096-44E7-49d1-B082-739671D2B12A)
]
library MsHtmlCustomization
{
import "MsHtmHst.idl";
import "Mshtml.idl";
....
enum tagDOCHOSTUIDBLCLK;
enum tagDOCHOSTUIFLAG;
enum tagDOCHOSTUITYPE;
enum tagSTGMEDIUM; //this don't rule... dont import the enum
....
interface IDataObject;
interface HTMLDocumentEvents2;
};

i'm working with a custom MsHtml and i need to control a dragEnter Event of
this COM so i implement the interface HTMLDocumentEvents2

....
public override void DragEnter(MsHtmlCustomization.IDataObject pDataObj,
uint grfKeyState, _POINTL pt, ref uint pdwEffect)
....

but when i see the dll (with ildasm) the method getdata of IDataObject has
been replaced by RemoteGetData:

public hidebysig newslot virtual abstract
instance void RemoteGetData([in] valuetype
MsHtmlCustomization.tagFORMATETC& pformatetcIn,
[out] native int pRemoteMedium) runtime
managed internalcall

you can see that the pointer to STGMEDIUM is replaced by int pRemoteMedium.

i call to remotegetdata with this code but break:

System.IntPtr STGMEDIUM;
pDataObj.RemoteGetData(ref fmtetc,STGMEDIUM);

the COM must receive a pointer to an STGMEDIUM structure but C# get an
integer.

is a problem of marshalling? is a bug?

some solution for to read the STGMEDIUM of the IDataObject?

tnks in advanced.