请教各位大侠

我在网上下载了一个读取usb设备的例程。
可是编译后出现这样的错误信息，请问哪位知道是什么原因么？谢谢。

--------------------Configuration: USBPort - Win32 Debug--------------------


Compiling...
USBPortDlg.cpp
Generating Code...
Compiling...
USBPort.cpp
Generating Code...
Linking...
USBPortDlg.obj : error LNK2001: unresolved external symbol \"unsigned char __stdcall HidD_GetAttributes(void *,struct _HIDD_ATTRIBUTES *)\" (?HidD_GetAttributes@@YGEPAXPAU_HIDD_ATTRIBUTES@@@Z)
USBPortDlg.obj : error LNK2001: unresolved external symbol __imp__SetupDiGetDeviceInterfaceDetailA@24
USBPortDlg.obj : error LNK2001: unresolved external symbol __imp__SetupDiDestroyDeviceInfoList@4
USBPortDlg.obj : error LNK2001: unresolved external symbol __imp__SetupDiEnumDeviceInterfaces@20
USBPortDlg.obj : error LNK2001: unresolved external symbol __imp__SetupDiGetClassDevsA@16
USBPortDlg.obj : error LNK2001: unresolved external symbol \"void __stdcall HidD_GetHidGuid(struct _GUID *)\" (?HidD_GetHidGuid@@YGXPAU_GUID@@@Z)
Debug/USBPort.exe : fatal error LNK1120: 6 unresolved externals
Error executing link.exe.