How to enumerate implemented interfaces correctly by IMetaDataImport::EnumInterfaceImpls

[o-lek]

I need to enumerate all implemented interfaces in a class, for example List.
Let's imagine that
ICorDebugType* ptList;
refers to the List type.
and
IMetadataImport* pMD;
points to IMetadataImport interface.

The code looks like that:
ICorDebugClass* ptListClass;
mdTypeDef metaTypeDef;
CorElementType ty;
HRESULT stat;
HCORENUM phEnum = NULL;
ULONG pcImpls;
mdInterfaceImpl rImpls[10];
stat = ptList->GetType(&ty);
if (ty == ELEMENT_TYPE_CLASS || ty == ELEMENT_TYPE_VALUETYPE)
{
stat = pType->GetClass(&ptListClass);
stat = ptListClass->GetToken(&metaTypeDef);
stat = pMD->EnumInterfaceImpls(&phEnum, metaTypeDef, rImpls, 10, &pcImpls);
}
The problem is that EnumInterfaceImpls returns S_FALSE that means it couldn't find any implemented interfaces and the counter pcImpls is 0.

In fact, class List implements several interfaces:

public partial class List : System.Collections.Generic.ICollection, System.Collections.Generic.IEnumerable, System.Collections.Generic.IList, System.Collections.Generic.IReadOnlyCollection, System.Collections.Generic.IReadOnlyList, System.Collections.ICollection, System.Collections.IEnumerable, System.Collections.IList

So, what am I doing wrong?