[Freeswitch-users] How to get mod_cdr_csv work properly

Hi all, mod_cdr_csv does log the call details to ./log/Master.csv file, however it will lose all the records when it rotate to Master.csv.[time stamp], it always create an empty file. The permission status showing on this empty file is -rw-------. I have give all the permission ( chmod +777) to ./log folder and still does not help. I and using SVN 7768 and start ./freeswitch when I login as root, all configuration is default. What else I need to do to keep the CDR in the history file? Thanks for your time, Steven Xu