Tooltips problem under 98

I have a big problem with toolbars tooltips queries under 98.

I have tooltips on toolbars in a CFrameWnd.

When tooltip is required a error occurs and this ONLY ON WINDOWS 98. The same code works well under NT.

The code line which crashes is in the method
'LRESULT CControlBar::WindowProc'


if ((pNMHDR->code == TTN_NEEDTEXTA && (!pTTTA->lpszText || !*pTTTA->lpszText)) ||
(pNMHDR->code == TTN_NEEDTEXTW && (!pTTTW->lpszText || !*pTTTW->lpszText)))




In fact it seems that the access to the pTTTW structure causes the error.
The pTTTW structure is for unicode text (NT only).

Does anyone know anything about this problemn ?