Private Sub Testfenster_Load(ByVal sender As Object, ByVal e As _
  System.EventArgs) Handles Me.Load
   Me.lst_Ergebnisse_Add(1, 10, "Text", "Soll", "Ist", "Pass", Color.Green)
End Sub

 
   Public Sub lst_Ergebnisse_Add(ByVal int_IconNr As Int16, ByVal int_ZeilenNr _
     As Int32, ByVal str_Text As String, ByVal str_SollText As String, ByVal _
     str_IstText As String, ByVal str_TestErgebnis As String, ByVal _
     col_Schriftfarbe As Color)
 
        Dim ListItem As New ListViewItem
        ListItem.UseItemStyleForSubItems = False
        Try
            'If Me.lst_Ergebnisse.InvokeRequired Then
            'Dim ext_lst_Ergebnisse_add As New dlg_lst_Ergebnisse_add(AddressOf 
            ' lst_Ergebnisse_Add)
            'Me.Invoke(ext_lst_Ergebnisse_add, New Object() {int_IconNr, 
            ' int_ZeilenNr, str_Text, str_SollText, str_IstText, 
            ' str_TestErgebnis, col_Schriftfarbe})
            'Else
            ListItem = Me.lst_Ergebnisse.Items.Add("", int_IconNr)
            ListItem.SubItems.Add(CStr(int_ZeilenNr))
            ListItem.SubItems.Add(str_Text)
            ListItem.SubItems.Add(str_SollText)
            ListItem.SubItems.Add(str_IstText)
            ListItem.SubItems.Add(str_TestErgebnis)
            ListItem.ForeColor = col_Schriftfarbe
            'End If
        Catch ex As System.Exception
            MessageBox.Show(ex.ToString)
        End Try
 
 
    End Sub

Try
  Testfenster.lst_Ergebnisse_Add(1, 10, "Text", "Soll", "Ist", "Pass", _
    Color.Green)
Catch ex As System.Exception
  MessageBox.Show(ex.ToString)
End Try