谁能给一个u盘卸载弹出的例子？

我的程序卸载u盘时只能够让u盘图标上面打个问号，但是u盘并没有弹出，盘还在转，u盘上面的灯还在亮着......
还得用鼠标右键那个任务栏上面的托盘图标，点击一次卸载，才把u盘卸掉了。如何能一步到位呢？我使用的代码如下所示，如果没有现成的历程的话，帮忙看下问题在哪里，怎么改？

int PopUDisk(CString UName)

{

	HANDLE   hDevice = NULL;//   handle   to   the   drive   to   be   examined  

	BOOL     bResult = FALSE;//   results   flag  

	DWORD    junk = 0;//   discard   results  

	DWORD    dwError = 0;

	int      Result = 0;



	CString strTemp = _T("\\\\.\\");

	strTemp+=UName;

	//   Open   the   volume  

	//hDevice   =   CreateFileW( "\\\\.\\I: ",//   drive   to   open

	hDevice   =   CreateFileW(strTemp,//   drive   to   open

		GENERIC_READ | GENERIC_WRITE,

		FILE_SHARE_READ | FILE_SHARE_WRITE,//   share   mode

		NULL,//        default   security   attributes

		OPEN_EXISTING,//   disposition

		0,//   file   attributes

		NULL);//   don 't   copy   any   file 's   attributes



	if(hDevice == INVALID_HANDLE_VALUE)//   can 't   open   the   drive  

	{  

		dwError   =   GetLastError();

		//AfxMessageBox( "Fail   to   create   file! ");  

		return 1;//创建文件设备句柄失败  

	}

	//Dismount   the   volume  

	bResult = DeviceIoControl(hDevice,//     handle   to   volume

		FSCTL_DISMOUNT_VOLUME,//             dwIoControlCode

		//IOCTL_STORAGE_EJECT_MEDIA,

		NULL,//                              lpInBuffer

		0,//                                 nInBufferSize

		NULL,//                              lpOutBuffer

		0,//                                 nOutBufferSize

		&junk,//                             discard   count   of   bytes   returned

		(LPOVERLAPPED)NULL);//               synchronous   I/O



	if(!bResult)//   IOCTL   failed  

	{  

		dwError   =   GetLastError();

		//AfxMessageBox( "Fail   to   dismount   the   volume! ");

		Result = 2;//卸载u盘失败！

	}  



	//   Close   the   volume   handle  

	bResult = CloseHandle(hDevice);

	if(!bResult) 

	{  

		dwError   =   GetLastError();  

		//AfxMessageBox( "Fail   to   close   handle! ");

		return 3;

	}



	return Result;//success result is 0

}