关于USB口的插拔检测解决办法

关于USB口的插拔检测
写一段关于USB口的插拔检测时 遇到一个问题 代码是

void __fastcall TForm1::OnDeviceChange(TMessage Message){

    PDEV_BROADCAST_HDR pHdr = (PDEV_BROADCAST_HDR)Message.LParam;

    GUID myGuid=GUID_DEVINTERFACE_MYSTM32USB;    //设备接口类GUID  在intrface.h文件中定义

    PDEV_BROADCAST_DEVICEINTERFACE pDevInf;

        if((DBT_DEVICEREMOVECOMPLETE==Message.WParam)||(DBT_DEVICEARRIVAL==Message.WParam))

        {

                switch(pHdr->dbch_devicetype)

                {

                    case DBT_DEVTYP_DEVICEINTERFACE:

                        pDevInf = (PDEV_BROADCAST_DEVICEINTERFACE)pHdr;

                        if(pDevInf->dbcc_classguid==myGuid)//判断拔出设备的设备接口类和usb2can设备

                                                            //的设备接口类是否一致

                        {

                                switch(Message.WParam)

                            {

                                case DBT_DEVICEREMOVECOMPLETE:

                                    Timer1->Enabled=false;

                                    Label1->Caption=Communication_State[0];

                                    Application->MessageBox("设备连接断开！请检查设备接线是否正确","警告信息",MB_OK);

                                    break;

                                case DBT_DEVICEARRIVAL:

                                    Application->MessageBox("检测到设备接入！","提示信息",MB_OK);

                                    HWInitial();

                                    FlushFIFO();

                                    ccp.ccpConnect();

                                    Label1->Caption=Communication_State[1];

                                    break;

                                default:break;

                            }

                      }


                        break;

                    case DBT_DEVTYP_HANDLE:

                        //Edit4->Text="HANDLE";

                        break;

                    case DBT_DEVTYP_OEM:

                        //Edit4->Text="OEM";

                        break;

                    case DBT_DEVTYP_PORT:

                        //Edit4->Text="PORT";

                        break;

                    case DBT_DEVTYP_VOLUME:

                       //Edit4->Text="VOLUME";  //U盘拔出响应

                        break;

                }

        }

}

运行后，插拔USB设备时，没有弹出窗，经检测是程序没有进入 if((DBT_DEVICEREMOVECOMPLETE==Message.WParam)||(DBT_DEVICEARRIVAL==Message.WParam)) 循环；请问是什么原因？
------解决思路----------------------
在if这一行加个断点，看看Message.WParam的值是多少。