LDAP Authentication

Question

I've made a little LDAP auth kit in ASP.NET project using C#. The code is based on an article I read about LDAP authentication: http://msdn.microsoft.com/library/default.asp? url=/library/en-us/dnnetsec/html/SecNetHT02.asp Look at Step 3 point 7 Everything seems to be in order though there is one weird thing I dont understand. If the auth. fails an exception is thrown. Why is that? Isn't the code suppose to generate false in this case. Any ideas? Regards Johannes