System.AccessViolationException: "Attempted to read or write protected memory. This is often an indication that other memory is corrupt."

//---------------------------------------
// Initialize
NET_DVR_Init();
//set connected time and reconnected time
NET_DVR_SetConnectTime(2000, 1);
NET_DVR_SetReconnect(10000, true);

//---------------------------------------
// Register device
LONG lUserID;

//Login parameters, including IP address, user name, password and so on.
NET_DVR_USER_LOGIN_INFO struLoginInfo = {0};
struLoginInfo.bUseAsynLogin = 0; //Synchronous login mode
strcpy(struLoginInfo.sDeviceAddress, "192.0.0.64"); //IP address
struLoginInfo.wPort = 8000; //Service port
strcpy(struLoginInfo.sUserName, "admin"); //User name
strcpy(struLoginInfo.sPassword, "abcd1234"); //Password

//Device information, output parameter
NET_DVR_DEVICEINFO_V40 struDeviceInfoV40 = {0};

lUserID = NET_DVR_Login_V40(&struLoginInfo, &struDeviceInfoV40);
if (lUserID < 0)
{
    printf("Login failed, error code: %dn", NET_DVR_GetLastError());
    NET_DVR_Cleanup();
    return;
}

public class HCNetSDK
{
    private const string origDllName = @"C:docsHCNetSDK.dll";

    #region structs
    [StructLayout(LayoutKind.Sequential)]
    public struct NET_DVR_DEVICEINFO_V30
    {
        public Byte[]   sSerialNumber;//[48];
        public Byte     byAlarmInPortNum;
        public Byte     byAlarmOutPortNum;
        public Byte     byDiskNum;
        public Byte     byDVRType;
        public Byte     byChanNum;
        public Byte     byStartChan;
        public Byte     byAudioChanNum;
        public Byte     byIPChanNum;
        public Byte     byZeroChanNum;
        public Byte     byMainProto;
        public Byte     bySubProto;
        public Byte     bySupport;
        public Byte     bySupport1;
        public Byte     bySupport2;
        public UInt16   wDevType;
        public Byte     bySupport3;
        public Byte     byMultiStreamProto;
        public Byte     byStartDChan;
        public Byte     byStartDTalkChan;
        public Byte     byHighDChanNum;
        public Byte     bySupport4;
        public Byte     byVoiceInChanNum;
        public Byte     byStartVoiceInChanNo;
        public Byte     bySupport5;
        public Byte     bySupport6;
        public Byte     byMirrorChanNum;
        public UInt16   wStartMirrorChanNo;
        public Byte     bySupport7;
        public Byte     byRes2;
    }
    #endregion



    [DllImport(origDllName)]
    public static extern Boolean NET_DVR_Init();

    [DllImport(origDllName)]
    public static extern Boolean NET_DVR_SetConnectTime(UInt32 dwWaitTime, UInt32 dwTryTimes);

    [DllImport(origDllName)]
    public static extern Boolean NET_DVR_SetReconnect(UInt32 dwInterval, Boolean bEnableRecon);

    [DllImport(origDllName)]
    public static extern Int32 NET_DVR_Login_V30(string sDVRIP, UInt16 wDVRPort, string sUserName, string sPassword, ref NET_DVR_DEVICEINFO_V30 DeviceInfo);

    [DllImport(origDllName)]
    public static extern UInt32 NET_DVR_GetLastError();

    [DllImport(origDllName)]
    public static extern Boolean NET_DVR_Cleanup();
}

static void Main(string[] args)
    {
        Camera.HCNetSDK.NET_DVR_Init();
        Camera.HCNetSDK.NET_DVR_SetConnectTime(2000, 1);
        Camera.HCNetSDK.NET_DVR_SetReconnect(10000, true);

        Int32 lUserID;

        Camera.HCNetSDK.NET_DVR_DEVICEINFO_V30 struDeviceInfoV30 = new Camera.HCNetSDK.NET_DVR_DEVICEINFO_V30();

        lUserID = Camera.HCNetSDK.NET_DVR_Login_V30("ip", 8000, "login", "pass", ref struDeviceInfoV30);

        if (lUserID < 0)
        {
            Console.WriteLine("Login failed, error code: {0}n", Camera.HCNetSDK.NET_DVR_GetLastError());
            Camera.HCNetSDK.NET_DVR_Cleanup();
            Console.ReadKey();
            return;
        }

        Console.WriteLine("The max number of analog channels: {0}n", struDeviceInfoV30.byChanNum);
        Console.WriteLine("The max number of IP channels: {0}n", struDeviceInfoV30.byIPChanNum + struDeviceInfoV30.byHighDChanNum * 256);

        Console.WriteLine("Done!");
        Console.ReadKey();
    }

LONG NET_DVR_Login_V30(
  char                       *sDVRIP,
  WORD                       wDVRPort,
  char                       *sUserName,
  char                       *sPassword,
  LPNET_DVR_DEVICEINFO_V30   lpDeviceInfo);

struct{
  BYTE     sSerialNumber[SERIALNO_LEN];  BYTE     byAlarmInPortNum;
  BYTE     byAlarmOutPortNum;            BYTE     byDiskNum;
  BYTE     byDVRType;                    BYTE     byChanNum;
  BYTE     byStartChan;                  BYTE     byAudioChanNum;
  BYTE     byIPChanNum;                  BYTE     byZeroChanNum;
  BYTE     byMainProto;                  BYTE     bySubProto;
  BYTE     bySupport;                    BYTE     bySupport1;
  BYTE     bySupport2;                   WORD     wDevType;
  BYTE     bySupport3;                   BYTE     byMultiStreamProto;
  BYTE     byStartDChan;                 BYTE     byStartDTalkChan;
  BYTE     byHighDChanNum;               BYTE     bySupport4;
  BYTE     byVoiceInChanNum;             BYTE     byStartVoiceInChanNo;
  BYTE     bySupport5;                   BYTE     bySupport6;
  BYTE     byMirrorChanNum;              WORD     wStartMirrorChanNo;
  BYTE     bySupport7;                   BYTE     byRes2;
}NET_DVR_DEVICEINFO_V30,*LPNET_DVR_DEVICEINFO_V30;