How to use ownerdrawn ccombobox in MyCdialog class

[Beginner_MFC]

I have derived a class from CComboBox.I want to change background color of selected/hovered string in CComboBox to Red.
Below is code of .h and .cpp files of derived class.

//MyCCombo.h

#include "Stdafx.h"

class MyCCombo : public CComboBox 
{
public:
MyCCombo();
~MyCCombo();

protected:
virtual void DrawItem(LPDRAWITEMSTRUCT lpDrawItemStruct);
DECLARE_MESSAGE_MAP()
};

//MyCCombo.cpp

void MyCCombo::DrawItem(LPDRAWITEMSTRUCT lpDrawItemStruct)
{
   ASSERT(lpDrawItemStruct->CtlType == ODT_COMBOBOX);
   LPCTSTR lpszText = (LPCTSTR)lpDrawItemStruct->itemData;
   ASSERT(lpszText != NULL);
   CDC dc;

   dc.Attach(lpDrawItemStruct->hDC);

   // Save these value to restore them when done drawing.
   COLORREF crOldTextColor = dc.GetTextColor();
   COLORREF crOldBkColor = dc.GetBkColor();

   // If this item is selected, set the background color
   // and the text color to appropriate values. Erase
   // the rect by filling it with the background color.
   if ((lpDrawItemStruct->itemAction & ODA_SELECT) &&
       (lpDrawItemStruct->itemState & ODS_SELECTED))
   
 {
      dc.SetTextColor(RGB(33,33,33));
      dc.SetBkColor(RGB(255,0,0));
      dc.FillSolidRect(&lpDrawItemStruct->rcItem, RGB(255,0,0));
   }
   else
   {
      dc.FillSolidRect(&lpDrawItemStruct->rcItem, crOldBkColor);
   }


   dc.Detach();
}

Now in MyCdialog(derived from Cdialog).h ,i include the #MyCComboBox.h and declared the variable of type MyCComboBox m_box; and used m_box in MyCdialog.cpp through DDX mapping
But result is not reflected..