Unknow Window Creation Error ?

#include <Windows.h>

LRESULT CALLBACK WinProc(HWND hWnd,UINT uMsg,WPARAM wParam,LPARAM lParam);

const LPWSTR szClassName = L"ClassName"; 
const LPWSTR szTitle = L"Window Tile"; 
int HEIGHT = 600;
int WIDTH = 800;


int WINAPI WinMain(HINSTANCE hInstance,HINSTANCE hPrevInstance,LPSTR lpCmdLine,int nCmdShow)
{
	WNDCLASSEX wc;
	HWND hWnd = NULL;
	MSG msg = {0};
	wc.cbSize = sizeof ( WNDCLASSEX);
	wc.hInstance = hInstance;
	wc.cbClsExtra = 0;
	wc.cbWndExtra = 0;
	wc.hbrBackground = (HBRUSH) GetStockObject( NULL_BRUSH );
	wc.hCursor = LoadCursor ( hInstance, IDC_CROSS );
	wc.hIcon = LoadIcon ( NULL, MAKEINTRESOURCE(IDI_APPLICATION) );
	wc.hIconSm = LoadIcon ( NULL, MAKEINTRESOURCE(IDI_WINLOGO) );
	wc.lpfnWndProc = WinProc;
	wc.lpszClassName = szClassName;
	wc.lpszMenuName = NULL;
	wc.style = CS_HREDRAW | CS_VREDRAW;

	if ( !RegisterClassEx( &wc ) )
		{
        MessageBox(NULL,
            L"Class Registration Failed",
			L"Error:1",
            NULL);

        return 1;
    }

	hWnd = CreateWindow(
        szClassName,
        szTitle,
        WS_OVERLAPPEDWINDOW,
        CW_USEDEFAULT, CW_USEDEFAULT,
        500, 100,
        NULL,
        NULL,
        hInstance,
        NULL
    );

	if (!hWnd)
    {
        MessageBox(NULL,
            L"Call to CreateWindow failed!",
			L"Error: 2",
            NULL);

        return 1;
    }
	
	ShowWindow(hWnd,nCmdShow);
	UpdateWindow(hWnd);

	while (GetMessage(&msg, NULL, 0, 0))
    {
        TranslateMessage(&msg);
        DispatchMessage(&msg);
    }
	return (int)msg.wParam;
}
LRESULT CALLBACK WinProc(HWND hWnd,UINT uMsg,WPARAM wParam,LPARAM lParam)
{
	switch( uMsg )
	{
	case WM_DESTROY:
		PostQuitMessage(0);
		return 0;
		break;
	case WM_CHAR:
			switch( wParam )
			{
			case VK_ESCAPE:
				PostQuitMessage(0);
				return 0;
				break;
			}
	default:
		DefWindowProc(hWnd,uMsg,wParam,lParam);

	}
	return 0;
}