Thanks very much for your post. Can I first check--is the log4net.config file copied over to the new directory of the obfuscated exe? I don't believe that SmartAssembly will automatically copy over the log4net.config file.
Should that not be the issue, could you kindly try building the application in SA again but will all options (merging, obfuscation, etc..) turned off? Please let me know if the log file still does not get created in that case.
Red Gate Software Ltd.