Imports System.Diagnostics
 
Public Class Form1
 
    Private EreignisKategorie As String = "est"
    Private Quelle As String = "Testanwendung"
 
    Private Sub btnCreateEvent_Click(ByVal sender As System.Object, ByVal e As _
      System.EventArgs) Handles btnCreateEvent.Click
        If Not EventLog.SourceExists(EreignisKategorie) Then
            ...
        End If
 
    End Sub
End Class