Problemer med at oprette vindue

Kode 

#include <windows.h>

const char g_szClassName[] = "myWindowClass";
HINSTANCE hInst;
HWND hWndMain;

LRESULT CALLBACK MainWndProc(HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam)
{
	switch (msg) {
		case WM_CLOSE:
			DestroyWindow(hWnd);
			break;
		case WM_DESTROY:
			PostQuitMessage(0);
			break;
		default:
			return DefWindowProc(hWnd, msg, wParam, lParam);
	}
	return 0;
}

static bool initApplication(void)
{
	WNDCLASS wc;

	memset(&wc, 0, sizeof(WNDCLASS));
	wc.style = CS_HREDRAW|CS_VREDRAW |CS_DBLCLKS;
	wc.lpfnWndProc = (WNDPROC)MainWndProc;
	wc.hInstance = hInst;
	wc.hbrBackground = (HBRUSH)(COLOR_WINDOW+1);
	wc.lpszClassName = (LPCWSTR)g_szClassName;
	wc.hCursor = LoadCursor(NULL,IDC_ARROW);
	wc.hIcon = LoadIcon(NULL,IDI_APPLICATION);
	if (!RegisterClass(&wc))
		return false;

	return true;
}

HWND createMainWndClassWnd(void)
{
	return CreateWindowA(g_szClassName, "Test Window",
						 WS_MINIMIZEBOX|WS_VISIBLE|WS_CLIPSIBLINGS|WS_CLIPCHILDREN|WS_MAXIMIZEBOX|
						 WS_CAPTION|WS_BORDER|WS_SYSMENU,
						 CW_USEDEFAULT,0,CW_USEDEFAULT,0,
						 NULL,
						 NULL,
						 hInst,
						 NULL);
}

int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance,
				   LPSTR lpCmdLine, int nShowCmd)
{
	MSG msg;

	hInst = hInstance;
	if (!initApplication()) {
		MessageBoxA(NULL, "initApplication: failed", "Error", MB_OK);	
		return 0;
	}

	if ((hWndMain = createMainWndClassWnd()) == (HWND)0) {
		MessageBoxA(NULL, "Failed to create window!", "Error", MB_OK);
		return 0;
	}

	ShowWindow(hWndMain, SW_SHOW);

	while (GetMessage(&msg, NULL, 0,0)) {
		TranslateMessage(&msg);
		DispatchMessage(&msg);
	}

	return msg.wParam;
}