Apache on Snow Leopard, "ulimit: open files: cannot modify limit: Invalid argument"

When I started apache on my Snow Leopard i got a weird exception

/usr/sbin/apachectl: line 82: ulimit: open files: cannot modify limit: Invalid argument


So I opened the script and found that there is something wrong with $ULIMIT_MAX_FILES

The error message says that 'cannot modify limit' so i changed its value to empty string

# ULIMIT_MAX_FILES="ulimit -S -n `ulimit -H -n`"
ULIMIT_MAX_FILES=""


Voila, it works, but deeper investigation need.