Network Devices & SetupAPI.DLL

I am trying to enumerate all the network adapters on a machine and then disable all of them except for one. I am trying to do this with setupapi.dll. I have some C# examples but I guess I am just converting the source code incorrectly. Here is what I currently have:

Code:

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    Private Declare Function SetupDiGetClassDevsW Lib "setupapi.dll" (ByRef ClassGUID As Guid, ByVal samDesired As Integer, ByVal Flags As Integer, ByVal hWndParent As String) As Integer
    Private Declare Function SetupDiEnumDeviceInterfaces Lib "setupapi.dll" (ByVal hDevInfo As IntPtr, ByRef devInfo As SP_DEVINFO_DATA, ByRef Guid As Guid, ByVal memberIndex As Integer, ByRef deviceInterfaceData As SP_DEVICE_INTERFACE_DATA) As Boolean
    Private Declare Function SetupDiGetDeviceInterfaceDetail Lib "setupapi.dll" (ByVal hDevInfo As IntPtr, ByRef DeviceInterfaceData As SP_DEVICE_INTERFACE_DATA, ByRef DeviceInterfaceDetailData As SP_DEVICE_INTERFACE_DETAIL_DATA, ByVal DataSize As Integer, ByVal RequiredSize As Integer, ByRef DeviceInfoData As SP_DEVINFO_DATA) As Boolean

    Const GUID_DEVINTERFACE_NETADAPT As String = "4D36E972-E325-11CE-BFC1-08002BE10318"
    Const DIGCF_PRESENT As Integer = &H2
    Const DIGCF_DEVICEINTERFACE As Integer = &H10

    Private NetAdapterGUID As Guid

    Private Structure SP_DEVINFO_DATA
        Dim cbSize As Integer
        Dim ClassGuid As Guid
        Dim DevInst As Integer
        Dim Reserved As IntPtr
    End Structure

    Private Structure SP_DEVICE_INTERFACE_DATA
        Dim cbSize As Integer
        Dim Guid As Guid
        Dim Flags As Integer
        Dim Reserved As IntPtr
    End Structure

    Private Structure SP_DEVICE_INTERFACE_DETAIL_DATA
        Dim cbSize As Integer
        Dim DevicePath As Char
    End Structure

    Private Sub frmMain_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
        Dim Handle As IntPtr
        Dim Dia As SP_DEVICE_INTERFACE_DATA
        Dim Da As SP_DEVINFO_DATA
        Dim Didd As SP_DEVICE_INTERFACE_DETAIL_DATA
        Dim Success As Boolean = True
        Dim i As Integer = 0
        Dim nRequiredSize = 0
        Dim nBytes As Integer = 1000

        NetAdapterGUID = New Guid(GUID_DEVINTERFACE_NETADAPT)

        Handle = SetupDiGetClassDevsW(NetAdapterGUID, 0, IntPtr.Zero, DIGCF_PRESENT Or DIGCF_DEVICEINTERFACE)

        While Success
            Dia = New SP_DEVICE_INTERFACE_DATA
            Dia.cbSize = Marshal.SizeOf(Dia)

            Success = SetupDiEnumDeviceInterfaces(Handle, Nothing, NetAdapterGUID, i, Dia)

            If Success Then
                Da = New SP_DEVINFO_DATA
                Da.cbSize = Marshal.SizeOf(Da)

                Didd = New SP_DEVICE_INTERFACE_DETAIL_DATA
                Dia.cbSize = 4 + Marshal.SystemDefaultCharSize

                MsgBox(SetupDiGetDeviceInterfaceDetail(Handle, Dia, Didd, nBytes, nRequiredSize, Da))
            End If

            i += 1

        End While
    End Sub

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The code is failing on Success = SetupDiEnumDeviceInterfaces(Handle, Nothing, NetAdapterGUID, i, Dia)

Does anyone have any ideas?