I want to run soem code by rolling a mouse wheel.

MFC, doc/view

In Mainframe header:
Code:
afx_msg BOOL OnMouseWheel (UINT nFlags, short zDelta, CPoint pt);
In source message map:
Code:
ON_WM_MOUSEWHEEL()
Event handler:
Code:
BOOL CMainFrame::OnMouseWheel (UINT nFlags, short zDelta, CPoint pt)
{	
	
	if (zDelta>0)
	{
		OnDemokey();
	}
	else
	{
		OnMinuskey();
	};	
	return TRUE;
};
If i roll forward my code cyling in "OnDemokey();" if i roll back - in "OnMinuskey();"

What have I do to make act of rolling the wheel to work like an ordinary key pressing?