It seems mongod dose not log anything to log file when it runs as windows service. When i start the following command from cmd, it generates the logfile and starts logging. If i use the same command with --service to start the service, mongod only creates the file, but dose not append any conent.

c:\MongoDb\bin\mongod --bind_ip=127.0.0.1 --dbpath=d:\MongoDb\data --logpath=d:\MongoDb\log\mongo.txt --logappend --verbose --service