Trouble with an icon size in CXTPTaskPanel

Hello All,
I have MFC project with task panel on my form.
I filled my task panel with appropriate tasks.
Now I want that the task panel group headers have icon size 16px, group items 32px.
I use this way:
CImageList pImList;
pImList.Create(32, 32, ILC_COLOR32|ILC_MASK, 0, 1);
...
m_taskPanel.GetImageManager()->SetIcons(pImList, 0, 0, CSize(32, 32));
m_taskPanel.SetIconSize(CSize(32, 32));
m_taskPanel.SetGroupIconSize(CSize(16, 16));

But group headers always have icon size 32 px as group items.
Please tell me how can I set icon size for group headers 16px but for group items 32 px.

Thanks.