MSDN上面的一段代码，我试了怎么运行是出错

[UPCCPU]

// CMyComboBox is my owner-drawn combo box derived from CComboBox. This
// example measures an item and sets the height of the item to twice the
// vertical extent of its text. The combo box control was created with
// the following code:
// pmyComboBox->Create( WS_CHILD|WS_VISIBLE|WS_BORDER|WS_HSCROLL|WS_VSCROLL|
CBS_SORT|CBS_OWNERDRAWVARIABLE,
CRect(10,10,200,200), pParentWnd, 1);
//
void CMyComboBox::MeasureItem(LPMEASUREITEMSTRUCT lpMeasureItemStruct)
{
ASSERT(lpMeasureItemStruct->CtlType == ODT_COMBOBOX);

if (lpMeasureItemStruct->itemID != (UINT) -1)
{
LPCTSTR lpszText = (LPCTSTR) lpMeasureItemStruct->itemData;
ASSERT(lpszText != NULL);
CSize sz;
CDC* pDC = GetDC();

sz = pDC->GetTextExtent(lpszText);

ReleaseDC(pDC);

lpMeasureItemStruct->itemHeight = 2*sz.cy;
}
}
为了使MeasureItem能够被调用，必须设置CBS_OWNERDRAWVARIABLE属性，但设置了该属性之后，编译通过之后，一运行就出错，去掉以后虽然没错但改变不了高度，请问高手这是哪儿的问题？

[topwork]

还要重载DrawItem，因为基类中的DrawItem里面只有一句代码ASSERT(FALSE);当然会出错了；

[UPCCPU]

重载DrawItem了，还是不行啊

[UPCCPU]

up