How to create child frame window in view?

When I created a frame window in a view window,
I have a problem on close the window or terminate the program.

How can I fix it!

----------------------
Definition ...........


class CExView : public CView
{
.....
.....

public:
CFrameWnd m_ChildFrame;

.....
.....
};





......Source code ........


int CExView::OnCreate(LPCREATESTRUCT lpCreateStruct)
{
if (CWnd ::OnCreate(lpCreateStruct) == -1)
return -1;

// TODO: Add your specialized creation code here
CRect rect(100, 100, 500, 500);
m_ChildFrame.CreateEx(0, NULL, "Child Frame",
WS_OVERLAPPEDWINDOW | WS_VISIBLE | WS_CHILD | WS_CAPTION,
rect, this, 0);
return 0;
}