Tracking tooltips don't display at all

I want to display a tooltip that changes as the mouse moves to
different positions in the client area showing the pixel co-ordinates
in the tooltip. So, the tool here is the whole client area. Following
is the code i picked up from MSDN and used "as is" , everything
(messages, mouse tracking) works fine but the problem is that no
tooltips are displayed.
Any help will be greatly appreciated.

Following is the code i'm using:

// code begins

#define _WIN32_WINNT 0x0501

#define WINVER 0x0501

#include <windows.h>
#include <commctrl.h>
#include <stdio.h>

int count;
TCHAR str[1000];

HWND g_hwndTrackingTT;
TOOLINFO g_toolItem;
HINSTANCE g_hInst;
BOOL g_TrackingMouse;

LRESULT CALLBACK WindowFunc(HWND,UINT,WPARAM,LPARAM);

HWND CreateTrackingToolTip(int toolID, HWND hDlg, char *pText);

TCHAR szWinName[] = TEXT("MyWin");

int WINAPI WinMain(HINSTANCE hThisInst,HINSTANCE hPrevInst,LPSTR
lpszArgs,int nWinMode)
{
    HWND hwnd;
    MSG msg;
    WNDCLASSEX wcl;
    INITCOMMONCONTROLSEX ic;
    BOOL ret;

    g_hInst = hThisInst;
    ic.dwSize = sizeof(INITCOMMONCONTROLSEX);
    ic.dwICC = ICC_STANDARD_CLASSES|ICC_BAR_CLASSES;
    ret = InitCommonControlsEx(&ic);
    wcl.cbSize = sizeof(WNDCLASSEX);
    wcl.hInstance = hThisInst;
    wcl.lpszClassName = szWinName;
    wcl.lpfnWndProc = WindowFunc;
    wcl.style = CS_HREDRAW|CS_VREDRAW;
    wcl.hIcon = LoadIcon(NULL,IDI_APPLICATION);
    wcl.hIconSm = NULL;
    wcl.hCursor = LoadCursor(NULL,IDC_ARROW);
    wcl.lpszMenuName = NULL;
    wcl.cbClsExtra = 0;
    wcl.cbWndExtra = 0;
    wcl.hbrBackground = (HBRUSH) GetStockObject(WHITE_BRUSH);
    if(!RegisterClassEx(&wcl)) return 0;
    hwnd = CreateWindowEx(
        WS_EX_WINDOWEDGE,
        szWinName,
        TEXT("Window Title"),
        WS_OVERLAPPEDWINDOW,
        CW_USEDEFAULT,
        CW_USEDEFAULT,
        CW_USEDEFAULT,
        CW_USEDEFAULT,
        HWND_DESKTOP,
        NULL,
        hThisInst,
        NULL
        );
    ShowWindow(hwnd,nWinMode);
    UpdateWindow(hwnd);

    while(GetMessage(&msg,NULL,0,0))
    {
        TranslateMessage(&msg);
        DispatchMessage(&msg);
    }
    return msg.wParam;
}
LRESULT CALLBACK WindowFunc(HWND hwnd,UINT message,WPARAM
wParam,LPARAM lParam)
{

    HDC hdc;
    PAINTSTRUCT ps;
    static int cxClient = 0, cyClient = 0, oldX, oldY;
    int newX, newY;
    char coords[12];
    POINT pt;

    switch(message){

    case WM_CREATE:

        g_hwndTrackingTT = CreateTrackingToolTip(456, hwnd, "");

        return 0;

    case WM_SIZE:

        cxClient = LOWORD(lParam);
        cyClient = HIWORD(lParam);

        return 0;

    case WM_PAINT:

        hdc = BeginPaint(hwnd, &ps);

        EndPaint(hwnd, &ps);

        return 0;

    case WM_MOUSELEAVE:

        // The mouse pointer has left our window.
        // Deactivate the ToolTip.
        SendMessage(g_hwndTrackingTT, TTM_TRACKACTIVATE, (WPARAM)
FALSE, (LPARAM)&g_toolItem);
        g_TrackingMouse = FALSE;
        return FALSE;

    case WM_MOUSEMOVE:

        if (!g_TrackingMouse)
        // The mouse has just entered the window.
        {
            // Request notification when the mouse leaves.
            TRACKMOUSEEVENT tme = { sizeof(TRACKMOUSEEVENT) };
            tme.hwndTrack = hwnd;
            tme.dwFlags = TME_LEAVE;
            TrackMouseEvent(&tme);

            // Activate the ToolTip.
            SendMessage(g_hwndTrackingTT, TTM_TRACKACTIVATE,
                (WPARAM)TRUE, (LPARAM)&g_toolItem);
            g_TrackingMouse = TRUE;
        }

        newX = LOWORD(lParam);
        newY = HIWORD(lParam);

        // Make sure the mouse has actually moved. The presence of the
ToolTip
        // causes Windows to send the message continuously.
        if ((newX != oldX) || (newY != oldY))
        {
            oldX = newX;
            oldY = newY;

            // Update the text.
            sprintf(coords, "%d, %d", newX, newY);
            g_toolItem.lpszText = coords;
            SendMessage(g_hwndTrackingTT, TTM_SETTOOLINFO, 0, (LPARAM)
&g_toolItem);

            // Position the ToolTip.
            // The coordinates are adjusted so that the ToolTip does
not
            // overlap the mouse pointer.
            pt.x = newX;
            pt.y = newY;
            ClientToScreen(hwnd, &pt);
            SendMessage(g_hwndTrackingTT, TTM_TRACKPOSITION,
                0, (LPARAM)MAKELONG(pt.x + 10, pt.y - 20));
        }
        return FALSE;

    case WM_DESTROY:

        PostQuitMessage(0);
        return 0;
    }
    return DefWindowProc(hwnd,message,wParam,lParam);
}

HWND CreateTrackingToolTip(int toolID, HWND hDlg, char *pText)
{
    // Create a ToolTip.
    HWND hwndTT = CreateWindowEx(WS_EX_TOPMOST,
        TOOLTIPS_CLASS, NULL,
        WS_POPUP | TTS_NOPREFIX | TTS_ALWAYSTIP,
        CW_USEDEFAULT, CW_USEDEFAULT,
        CW_USEDEFAULT, CW_USEDEFAULT,
        hDlg, NULL, g_hInst,NULL);

    if (!hwndTT)
    {
        return NULL;
    }

    // Set up tool information.
    // In this case, the "tool" is the entire parent window.
    g_toolItem.cbSize = sizeof(TOOLINFO);
    g_toolItem.uFlags = TTF_IDISHWND | TTF_TRACK | TTF_ABSOLUTE;
    g_toolItem.hwnd = hDlg;
    g_toolItem.hinst = g_hInst;
    g_toolItem.lpszText = pText;
    g_toolItem.uId = (UINT_PTR)hDlg;
    GetClientRect (hDlg, &g_toolItem.rect);

    // Associate the ToolTip with the tool window.
    SendMessage(hwndTT, TTM_ADDTOOL, 0, (LPARAM) (LPTOOLINFO)
&g_toolItem);
    return hwndTT;
}

// code ends

Thanks,
--Anurag.