Upgrading Application from Enterprise Library 5 to 6

I am upgrading an existing application from 5 to 6. My application is a .NET web application. I rely on Enterprise library to log any errors to the database (sql server).

My application also uses a custom database listener and a custom Logging Exception Handler (both in the form of separate .net projects within my solution).

So, I have 6 installed, and have added the following code to Application_Start-

             IConfigurationSource config = ConfigurationSourceFactory.Create();
        ExceptionPolicyFactory factory = new ExceptionPolicyFactory(config);
        Logger.SetLogWriter(new LogWriterFactory().Create());

        ExceptionManager exceptionManager = factory.CreateManager();

I get a System.NotImplementedException when it hits the Logger.SetLogWriter(new LogWriterFactory().Create()); line of code.

EDIT: More specific error details

 System.NotImplementedException was unhandled by user code
 HResult=-2147467263
 Message=Must be implemented by subclasses.
 Source=Microsoft.Practices.EnterpriseLibrary.Logging

What am I doing wrong?

Here is my web.config-

   <configSections>
<section name="exceptionHandling" type="Microsoft.Practices.EnterpriseLibrary.ExceptionHandling.Configuration.ExceptionHandlingSettings, Microsoft.Practices.EnterpriseLibrary.ExceptionHandling" requirePermission="true" />
<section name="loggingConfiguration" type="Microsoft.Practices.EnterpriseLibrary.Logging.Configuration.LoggingSettings, Microsoft.Practices.EnterpriseLibrary.Logging, Version=5.0.505.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" requirePermission="true" />
<section name="dataConfiguration" type="Microsoft.Practices.EnterpriseLibrary.Data.Configuration.DatabaseSettings, Microsoft.Practices.EnterpriseLibrary.Data, Version=5.0.505.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" requirePermission="true" />


 </configSections>
<loggingConfiguration name="" tracingEnabled="true" defaultCategory="General">
<listeners>
  <add name="Database Trace Listener" type="ExtendedPropertyDatabaseListener.ExtendedFormattedDatabaseTraceListener, ExtendedPropertyDatabaseListener" listenerDataType="ExtendedPropertyDatabaseListener.ExtendedFormattedDatabaseTraceListenerData, ExtendedPropertyDatabaseListener" databaseInstanceName="ablmprod" writeLogStoredProcName="Logging.WriteLog" addCategoryStoredProcName="Logging.AddCategory" formatter="Text Formatter" />
  <add name="Event Log Trace Listener" type="Microsoft.Practices.EnterpriseLibrary.Logging.TraceListeners.FormattedEventLogTraceListener, Microsoft.Practices.EnterpriseLibrary.Logging, Version=5.0.505.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" listenerDataType="Microsoft.Practices.EnterpriseLibrary.Logging.Configuration.FormattedEventLogTraceListenerData, Microsoft.Practices.EnterpriseLibrary.Logging, Version=5.0.505.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" source="Enterprise Library Logging" formatter="Text Formatter" />
</listeners>
<formatters>
  <add type="Microsoft.Practices.EnterpriseLibrary.Logging.Formatters.TextFormatter, Microsoft.Practices.EnterpriseLibrary.Logging, Version=5.0.505.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" template="Timestamp: {timestamp}{newline}&#xA;Message: {message}{newline}&#xA;Category: {category}{newline}&#xA;Priority: {priority}{newline}&#xA;EventId: {eventid}{newline}&#xA;Severity: {severity}{newline}&#xA;Title:{title}{newline}&#xA;Machine: {localMachine}{newline}&#xA;App Domain: {localAppDomain}{newline}&#xA;ProcessId: {localProcessId}{newline}&#xA;Process Name: {localProcessName}{newline}&#xA;Thread Name: {threadName}{newline}&#xA;Win32 ThreadId:{win32ThreadId}{newline}&#xA;Extended Properties: {dictionary({key} - {value}{newline})}" name="Text Formatter" />
</formatters>
<categorySources>
  <add switchValue="All" name="General">
    <listeners>
      <add name="Database Trace Listener" />
    </listeners>
  </add>
</categorySources>
<specialSources>
  <allEvents switchValue="All" name="All Events" />
  <notProcessed switchValue="All" name="Unprocessed Category" />
  <errors switchValue="All" name="Logging Errors &amp; Warnings">
    <listeners>
      <add name="Event Log Trace Listener" />
    </listeners>
  </errors>
</specialSources>
</loggingConfiguration>
<exceptionHandling>
  <exceptionPolicies>
  <add name="Policy">
    <exceptionTypes>
      <add name="All Exceptions" type="System.Exception, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" postHandlingAction="NotifyRethrow">
        <exceptionHandlers>
          <add name="Logging Exception Handler" type="CustomExceptionLoggingHandler.CustomExceptionLoggingHandler, CustomExceptionLoggingHandler" logCategory="General" eventId="100" severity="Error" title="Enterprise Library Exception Handling" formatterType="Microsoft.Practices.EnterpriseLibrary.ExceptionHandling.TextExceptionFormatter, Microsoft.Practices.EnterpriseLibrary.ExceptionHandling" priority="0" />
        </exceptionHandlers>
      </add>
    </exceptionTypes>
  </add>
</exceptionPolicies>
</exceptionHandling>

EDIT: Thanks to @lrb for getting me on the right path. Here is the code that worked-

protected void Application_Start()
{
    LoggingConfiguration loggingConfiguration = BuildLoggingConfig();
    LogWriter logWriter = new LogWriter(loggingConfiguration);
    Logger.SetLogWriter(logWriter, false);
    ExceptionPolicy.SetExceptionManager(exManager);

    // Create the default ExceptionManager object programatically
    exManager = BuildExceptionManagerConfig(logWriter);

    // Create an ExceptionPolicy to illustrate the static HandleException method
    ExceptionPolicy.SetExceptionManager(exManager);

           ...
}

private static LoggingConfiguration BuildLoggingConfig()
{
    // Formatters

    var config = new LoggingConfiguration();

    return config;
}

private static ExceptionManager BuildExceptionManagerConfig(LogWriter logWriter)
{
    var policies = new List<ExceptionPolicyDefinition>();

    var logAndWrap = new List<ExceptionPolicyEntry>
            {

                new ExceptionPolicyEntry(typeof (Exception),
                    PostHandlingAction.ThrowNewException,
                    new IExceptionHandler[]
                     {
                       new WrapHandler("An application error has occurred.",
                         typeof(APIAvailabilityException))
                     })
            };

    policies.Add(new ExceptionPolicyDefinition("Policy", logAndWrap));

    return new ExceptionManager(policies);
}

It has changed up a little. You just need a dummy ConfugurationSource. This defaults to everything as it was and works for me. Notice the optional ThrowIfSet parameter for the SetLogWriter method. The documentation states:

throwIfSet : true to throw an exception if the writer is already set; otherwise false. Defaults to true.

IConfigurationSource configurationSource = ConfigurationSourceFactory.Create();
LogWriterFactory logWriterFactory = new LogWriterFactory(configurationSource);                
Logger.SetLogWriter(logWriterFactory.Create(),false);
Logger.Write(le);