problems with DeviceIoControl in VB.net

Hi. I am trying to convert this code written in VC++ (unmanaged) to VB .NET (managed). Could anyone please help?

// set configuration - MUST be set to do a RESET
if( !DeviceIoControl( DevHandle, IOCTL_USBIO_SET_CONFIGURATION,
&config, sizeof(config), NULL, 0, &dw, NULL ) )

where config is
typedef struct _USBIO_INTERFACE_SETTING {
USHORT InterfaceIndex;
USHORT AlternateSettingIndex;
ULONG MaximumTransferSize;
} USBIO_INTERFACE_SETTING;

typedef struct _USBIO_SET_CONFIGURATION {
USHORT ConfigurationIndex;
USHORT NbOfInterfaces;
USBIO_INTERFACE_SETTING InterfaceList[USBIO_MAX_INTERFACES];
} USBIO_SET_CONFIGURATION;
and
#define IOCTL_USBIO_SET_CONFIGURATION _USBIO_IOCTL_CODE(9,METHOD_BUFFERED)

#define FILE_DEVICE_USBIO 0x8094

//
// Macros to generate IOCTL codes.
// Note that function codes 0-2047 are reserved for Microsoft, and
// 2048-4095 are reserved for customers.
//
#define _USBIO_IOCTL_BASE 0x800

#define _USBIO_IOCTL_CODE(FnCode,Method) \
( (ULONG)CTL_CODE( \
(ULONG)FILE_DEVICE_USBIO, \
(ULONG)(_USBIO_IOCTL_BASE+(FnCode)), \
(ULONG)(Method), \
(ULONG)FILE_ANY_ACCESS \
) )

My translation of this code is below but doesn't work. I am having troubles getting a valid intPtr pointer for config with the correct size. how do we translate this code using mashal class? I tried Marshal.StructureToPtr, I tried Marshal.Copy. Nothing worked! I tried to make classes instead of stuctures and use another overloaded DeviceIOControl() from kernel32.dll. In vain...

The device in question is a spectrometer attached to the usb port. The C++ code works.

My translation:
<StructLayout(LayoutKind.Sequential)> _
Structure USBIO_INTERFACE_SETTING
Dim InterfaceIndex As UShort 'UShort
Dim AlternateSettingIndex As UShort 'ushort
Dim MaximumTransferSize As ULong 'ulong
End Structure


<StructLayout(LayoutKind.Sequential)> _
Structure USBIO_SET_CONFIGURATION
Public ConfigurationIndex As UShort
Public NbOfInterfaces As UShort
' <MarshalAs(UnmanagedType.LPArray, SizeConst:=32)> Dim InterfaceList() As USBIO_INTERFACE_SETTING
Public InterfaceList() As USBIO_INTERFACE_SETTING
End Structure

<DllImport("kernel32.dll", ExactSpelling:=True, SetLastError:=True, CharSet:=CharSet.Auto)> _
Private Shared Function DeviceIoControl(ByVal hDevice As IntPtr, _
ByVal dwIoControlCode As Int32, ByVal lpInBuffer As IntPtr, _
ByVal nInBufferSize As Int32, ByVal lpOutBuffer As IntPtr, _
ByVal nOutBufferSize As Int32, ByRef lpBytesReturned As Int32, _
ByVal lpOverlapped As Overlapped) As Boolean
End Function

......
Dim config As USBIO_SET_CONFIGURATION = New USBIO_SET_CONFIGURATION
config.ConfigurationIndex = 0
config.NbOfInterfaces = 1
ReDim config.InterfaceList(32)
Dim u As New USBIO_INTERFACE_SETTING()
u.InterfaceIndex = 0
u.AlternateSettingIndex = 0
u.MaximumTransferSize = 64
config.InterfaceList(0) = u

'config.InterfaceList(0) = New USBIO_INTERFACE_SETTING()
'config.InterfaceList(0).InterfaceIndex = 0
'config.InterfaceList(0).AlternateSettingIndex = 0
'config.InterfaceList(0).MaximumTransferSize = 64

Dim configAddress As IntPtr = Marshal.AllocHGlobal(Marshal.SizeOf(config))

'Dim configAddress As IntPtr = Marshal.AllocCoTaskMem(Marshal.SizeOf(config))

Dim ConfigByte() As Byte
ReDim ConfigByte(Marshal.SizeOf(config) - 1)
Marshal.Copy(ConfigByte, 0, configAddress, Marshal.SizeOf(config))

'Marshal.StructureToPtr(config, configAddress, False)
'ZeroMemory(configAddress)

Dim usbio As usbio_i = New usbio_i()
'set configuration - MUST be set to do a RESET
Dim succeeded As Boolean = DeviceIoControl(devHandle, usbio.IOCTL_USBIO_SET_CONFIGURATION, configAddress, Marshal.SizeOf(config), Nothing, 0, dw, Nothing)
If Not succeeded Then
status = Marshal.GetLastWin32Error()
If status <> usbioerr.USBIO_ERR_ALREADY_CONFIGURED Then

LastError = "IOCTL_USBIO_SET_CONFIGURATION - 0x&#37;08l" & status
CloseHandle(devHandle)
Return False
End If
End If

......

Public ReadOnly IOCTL_USBIO_SET_CONFIGURATION As Int32 = _
CTL_CODE(FILE_DEVICE_USBIO, _USBIO_IOCTL_BASE + 9, METHOD_BUFFERED, FILE_ANY_ACCESS)

Please, please anybody help? When do we use Marshal.Copy and when Marshal.StructureToPtr?
How do we handle structures that have embedded stuctures?
And how do we use MarshalAs in a struct?
It is all very confusing to me and nothing I tried worked. Please advice. thank you in advance.

Adria