When IRichEditOleCallback::QueryInsertObject was invoked, got an wrong CLSID

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C++

ATL

WTL

COM

I am making a atl control in which I can show image in richedit. To support copy & paste I implemented :

public IPersistStreamInitImpl<cmyimagectrl>,
public IPersistStorageImpl<cmyimagectrl>


and override
HRESULT IPersistStreamInit_Load(LPSTREAM pStm, const ATL_PROPMAP_ENTRY* pMap);
HRESULT IPersistStreamInit_Save(LPSTREAM pStm, BOOL fClearDirty, const ATL_PROPMAP_ENTRY* pMap);


Something wrong occurred when pasting, IPersistStreamInit_Load was never called. Then I found IRichEditOleCallback::QueryInsertObject's first parameter value was CLSID_Picture but not the one I defined.

I'm a new hand at atl & com, so I don't know what the essential mistake I have made ?