Here is my checklist for when log4net is proving to be recalcitrant:
- ensure that log4net.config file is copied to the bin\ folder when building (set to 'Copy if newer' in compiler)
- when dealing with installed code, ensure that the log4net.config came along for the ride (set to 'Content' in compiler)
- ensure that the user that the process runs as has write rights to the folder where the logs are to be written
- if in doubt, give promiscuous permissions to c:\temp\ and get everything to log to there ()
- fire up Sysinternal/Dbgview.exe to see if that tells you anything