Gaps on the graph when using poller spine

[quandv9]

I'm facing the cacti graph display after migrate to the new server. I got successful for migrating the old rrd files and it's showing graph ok ,but when i add the new graph,i see problem with display.
The graph not show at a few minutes as below:



How can i fix this problem.

[quandv9]

I change the poller type to cmd.php instead of spine,it's showing good now.
Anybody help to explain this,what's wrong with spine.
I install spine 0.8.8b as the introduction via https://alexzeng.wordpress.com/2012/12/ ... for-cacti/

[cgu]

hi, you can try to activate the logging in debug mode, let it run a few cycles and search for ERROR, WARNING or FATAL in the log to see if something went wrong.

[quandv9]

I start spine and getting the errors below,is it affect to the gaps?

PHP Warning: date(): It is not safe to rely on the system's timezone settings. You are *required* to use the date.timezone setting or the date_default_timezone_set() function. In case you used any of those methods and you are still getting this warning, you most likely misspelled the timezone identifier. We selected 'Asia/Bangkok' for 'ICT/7.0/no DST' instead in /usr/share/cacti/include/global_arrays.php on line 675

[quandv9]

I fixed by upgrade cacti-spine to 0.8.8f and change the poller setting (Maximum Concurrent Poller Processes from 8 to 4)