Не создается дочернее окно

#define  STRICT
#define  WIN32_LEAN_AND_MEAN // Exclude rarely-used stuff from Windows headers
 
#include <Windows.h>
LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam);
LRESULT CALLBACK ChildWndProc(HWND, UINT, WPARAM, LPARAM);
int APIENTRY WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance,
    LPSTR     lpCmdLine, int       nCmdShow)
{
    
    LPCTSTR szClass = TEXT("DiskTester32");
 
    WNDCLASS wc = { 0 };
    wc.lpfnWndProc = WndProc;
    wc.hInstance = hInstance;
    wc.lpszClassName = szClass;
 
    ::RegisterClass(&wc);
 
    // Create Main window
    HWND wmain = ::CreateWindow(szClass, "Overlapped", WS_OVERLAPPEDWINDOW | WS_CLIPCHILDREN | WS_CLIPSIBLINGS,
        0, 0, 400, 200, NULL, NULL, hInstance, NULL);
    if (!wmain) {
        return -1;
    }
 
    ShowWindow(wmain, nCmdShow);
    //Create PopUp window
    HWND popup= ::CreateWindow(szClass, "PopUp", WS_CAPTION | WS_POPUPWINDOW,
        0, 400, 200, 200, NULL, NULL, hInstance, NULL);
    if (!popup)
    {
        MessageBox(NULL, "Can`t create popup window", "Error!", MB_OK);
        return 0;
    }
    ShowWindow(popup, nCmdShow);
    
    //Create Child window
    static LPCSTR lpszChildClassName = "ChildWindow";
    static LPCSTR lpszChildWndText = "Child";
    HWND child = ::CreateWindow(lpszChildClassName, lpszChildWndText, WS_CHILD | WS_CAPTION | WS_VISIBLE | WS_SYSMENU | WS_MINIMIZEBOX | WS_MAXIMIZEBOX,
        0, 0, 200, 100, NULL, NULL, hInstance, NULL);
    if (!child)
    {
        MessageBox(NULL, "Can`t create child window", "Error!", MB_OK);
        return 0;
    }
    ShowWindow(child, nCmdShow);
 
    MSG msg;
    while (::GetMessage(&msg, NULL, 0, 0)) {
        ::DispatchMessage(&msg);
    }
 
    return 0;
}
//=========================================================
 
LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
    switch (message) {
 
    case WM_DESTROY:
        ::PostQuitMessage(0);
        return 0;
    }
 
    return ::DefWindowProc(hWnd, message, wParam, lParam);
}
//=========================================================