NLog Event Log Target: problems with Source/Provider Name & message format
===

I'm trying to use NLog to log events for a new application to a file and to the Event Log. I'm almost there, but not quite - I can get events logged to the Event Log, and in the Details/XML view (of the Event Log) everything looks OK. But in the General tab of the viewer, I don't get the event message displayed as expected; instead I get "DRGImporterError"; this matches which happens to be the SymbolicName (see below) from my EventLogMessages.mc file, but when I modified this value and recompiled the error message file, this didn't change. The event log source is 'DRGImporter' as is the application name, so I can't be sure what 'DRGImporterError' actually refers to!

I've manually created and edited the registry entries storing the EventMessageFile location: `HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\eventlog\MyAppLog\DRGImporter`. Originally, I pointed this key to my custom EventLogMessages.dll, but in trying to debug it, I also set it to one of the standard DLLs under `\Windows\Microsoft.NET\...`, but it didn't change the outcome.

I have a number of other applications using the same event log, but these use a different logging framework. Nevertheless they work, but more curiously, if I change the source that NLog points to to one of these older ones, NLog entries are logged successfully and the General view in the event log shows the expected text. The only difference I can see from the XML view is the EventRecordID and the timestamp, which is to be expected.

Is there another element to this equation that I am missing? 

EventLogMessages.mc:

    ;//***********Event Definitions**************
    MessageId=2000
    SymbolicName=MailerError
    Language=English
    %1.
    .
    MessageId=2100
    SymbolicName=DRGImporterError
    Language=English
    %1.
    .

NLog.config:

    <?xml version="1.0" encoding="utf-8" ?>
    <nlog xmlns="http://www.nlog-project.org/schemas/NLog.xsd"
    			xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" throwExceptions="true" autoReload="true" internalLogFile="nlog.log" internalLogLevel="Debug">

	<targets>
		<target name="eventLogHeaderTarget" xsi:type="EventLog" log="Hexadex" source="DRGImporter" eventId="0" layout="${message}" />
	</targets>

	<rules>
		<logger name="appLogHeader" minlevel="Debug" writeTo="eventLogHeaderTarget" />
    </rules>
