WMI call to add TCP/IP Printer port

Hi,

I have a vbscript that adds a printer.

strComputer = "."
Set objWMIService = GetObject("winmgmts:" _
    & "{impersonationLevel=impersonate}!\\" & strComputer & "\root\cimv2")
objWMIService.Security_.Privileges.AddAsString "SeLoadDriverPrivilege", True 

Install "192.168.5.150" 

sub Install(strIP)
    InstallPrinterPort strIP
end Sub 

strBasePrinter = "Copier"
strPrinterName = "RICOH IM C6000 PCL 6"
strINFPath = "C:\Printers\IMC6000\disk1\OEMSETUP.INF"
strIPPort = "IP_192.168.5.150"
Set objShell = CreateObject("WScript.Shell")
strCommand = "cmd /c rundll32 printui.dll,PrintUIEntry /if /b """ & strBasePrinter & """ /f " & strINFPath & " /r """ & strIPPort & """ /m """ & strPrinterName & """ & /Z"
objShell.Run strCommand, 1, True

Sub InstallPrinterPort(strIP)


    Set colInstalledPorts =  objWMIService.ExecQuery _
        ("Select Name from Win32_TCPIPPrinterPort")
    For each objPort in colInstalledPorts
        If objPort.Name="IP_" & strIP then exit sub 
    Next


    Set objNewPort = objWMIService.Get _
        ("Win32_TCPIPPrinterPort").SpawnInstance_
    objNewPort.Name = "IP_" & strIP
    objNewPort.Protocol = 1
    objNewPort.HostAddress = strIP
    objNewPort.PortNumber = "9100"
    objNewPort.SNMPEnabled = False
    objNewPort.Put_
end Sub

I'm trying to do the same now in vb.NET, with these two functions:

Private Function CreatePrinterIP(ByVal IPPort As String, ByVal IPPortName As String)
        Try
            Dim searcher As New ManagementObjectSearcher(
                    "root\CIMV2",
                    "SELECT * FROM Win32_TCPIPPrinterPort")

            For Each queryObj As ManagementObject In searcher.Get()

                If queryObj("Name") = IPPortName Then
                    Return 1
                    Exit Function
                End If
            Next

            Dim objNewPort As ManagementObject = searcher.Get("Win32_TCPIPPrinterPort").SpawnInstance()

            objNewPort("Name") = IPPortName

            objNewPort("Protocol") = 1

            objNewPort("HostAddress") = IPPort

            objNewPort("PortNumber") = "9100"

            objNewPort("SNMPEnabled") = False

            objNewPort.Put()
            Return 1
        Catch err As ManagementException
            MessageBox.Show("An error occurred while querying for WMI data: " & err.Message)
            Return 0
        End Try
    End Function

    Private Sub CreatePrinter(ByVal IPPortName As String, ByVal PrinterName As String, ByVal Location As String, ByVal Drivername As String)
        Dim cmdToSend As String = "rundll32 printui.dll,PrintUIEntry /if /b """ & Printername & """ /f " & Location & " /r """ & IPPortName & """ /m """ & Drivername & """ & /Z"
        Shell(cmdToSend)
    End Sub

The CreatePrinterIP function worked once.
I then deleted the IP adress manually. And tried again. Now I receive an error that

The conversion of string Win32_TCPIPPrinterPort to type Integer is invalid.

on line

Dim objNewPort As ManagementObject = searcher.Get("Win32_TCPIPPrinterPort").SpawnInstance()

Does anyone have an idea how to solve this?

Thanks!