Error setting system time with real-time clock

[Kirk]

I have a DS3231 real-time clock connected to my Beagelbone Black.

I have these lines in /etc/rc.local to initialize the system time from the RTC:

echo ds1307 0x68 > /sys/class/i2c-adapter/i2c-1/new_device

sleep 5

/sbin/hwclock -s -f /dev/rtc1

/sbin/hwclock -w

It almost always works correctly however:

Infrequently at boot up the hwclock commands fail and then the rest of rc.local doesn't run.

Here's the error output I captured from rc.local:

hwclock: Timed out waiting for time change.

hwclock: The Hardware Clock does not contain a valid time, so we cannot set the System Time from it.

Unable to set system clock.

Any idea on what could cause this error?

Thanks,

Kirk