有问题啊，怎么没有声音呢

#include <Windows.h>
//必须加上这两个东西
#include<mmsystem.h>
#pragma comment(lib,"winmm.lib")

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

int WINAPI WinMain(
HINSTANCEhInstance,
HINSTANCEhPrevInstance,
PSTRszCmdLine,
intiCmdShow
)
{
static TCHAR szAppName[] = TEXT("Hello, 晓东");
HWNDhwnd;
MSGmsg;
WNDCLASSwndclass;

wndclass.style= CS_HREDRAW | CS_VREDRAW;
wndclass.lpfnWndProc= WndProc;
wndclass.cbClsExtra= 0;
wndclass.cbWndExtra= 0;
wndclass.hInstance= hInstance;
wndclass.hIcon= LoadIcon(NULL, IDI_APPLICATION);
wndclass.hCursor= LoadCursor(NULL, IDC_ARROW);
wndclass.hbrBackground= (HBRUSH) GetStockObject (WHITE_BRUSH);
wndclass.lpszMenuName= NULL;
wndclass.lpszClassName= szAppName;

if (!RegisterClass (&wndclass))
{
MessageBox (NULL, TEXT ("This program requires Windows NT!"),
szAppName, MB_ICONERROR);
return 0;
}

hwnd = CreateWindow(
szAppName,
TEXT ("by:晓东"),
WS_OVERLAPPEDWINDOW,
CW_USEDEFAULT,
CW_USEDEFAULT,
CW_USEDEFAULT,
CW_USEDEFAULT,
NULL,
NULL,
hInstance,
NULL
);

ShowWindow (hwnd, iCmdShow);
UpdateWindow (hwnd);

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

LRESULT CALLBACK WndProc (HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
HDChdc;
PAINTSTRUCT ps;
RECTrect;

switch (message)
{
case WM_CREATE:
PlaySound (TEXT ("F:\\code\\windows\\windows\\windows\\debug\\back.wav"), NULL, SND_FILENAME | SND_ASYNC | SND_LOOP);
return 0;

case WM_PAINT:
hdc = BeginPaint (hwnd, &ps);

GetClientRect (hwnd, &rect);

DrawText (hdc, TEXT ("Hello, 晓东！"), -1, &rect,
 DT_SINGLELINE | DT_CENTER | DT_VCENTER);
EndPaint (hwnd, &ps);
return 0;

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