Saving OCAF Documents

Me Again!
Now that I have got the app to run, I can't get it to save an OCAF document.
Can anybody see where I am going wrong?
I am implementing under OnSaveDocument. Code is listed below.

BOOL CLeonardoDoc::OnSaveDocument(LPCTSTR lpszPathName)
{
// TODO: Add your specialized code here and/or call the base class

int res = CDocument::OnSaveDocument(lpszPathName);

//
// Saving OCAF Document

// Get OCAF Application
Handle(TLeo_Application) LeoApp= ((CLeonardoApp*)AfxGetApp())->GetApp();
CString extension = "leo";
CString CSPath(lpszPathName);

// If extension not defined add defalult extension
if(CSPath.Find('.') == -1 ) {
// Remove file without extension
CFile::Remove(lpszPathName);
CSPath += "." + extension;
}

Standard_CString SPath = (Standard_CString)(LPCTSTR) CSPath;
TCollection_ExtendedString TPath(SPath);

// Saves the document in the current application
LeoApp->SaveAs(myOcafDoc,TPath);

return res;
}

My OnNewDocument code:-

BOOL CLeonardoDoc::OnNewDocument()
{
if (!CDocument::OnNewDocument())
return FALSE;

// TODO: add reinitialization code here
// (SDI documents will reuse this document)

Handle(TLeo_Application) LeoApp = ((CLeonardoApp*)AfxGetApp())->GetApp();

// Create a new Ocaf document
LeoApp->NewDocument("Leo",myOcafDoc);
TPrsStd_AISViewer::New(myOcafDoc->Main(),myViewer);

Handle(AIS_InteractiveContext) CTX;
TPrsStd_AISViewer::Find(myOcafDoc->Main(), CTX);
CTX->SetDisplayMode(AIS_Shaded);
myAISContext=CTX;

return TRUE;
}

Many Thanks

Steve Howgill