RRD files not created for cacti.sql default, localhost graphs?

I'm having some trouble creating RRD files for the default, localhost 
graphs included in cacti.sql

I extracted Cacti 0.8.8a, created a database, and populated it with "$ 
mysql -u cacti -p cacti < cacti.sql". Then I visited my Cacti URL and 
walked through the web based installer, which completed successfully

At this point I notice there is a default, localhost device that I guess 
is included in cacti.sql? I added a bunch of additional devices and 
graphs, then I checked the Cacti "rra" directory and notice that it is 
still empty, no RRD files are created yet for either the default, 
localhost graphs or the graphs added by me

Finally I run poller.php and notice that the Cacti "rra" directory is 
now full of RRD files for all the graphs added by me, but *not* for 
default, localhost graphs. When I visit the default, localhost device 
with the web interface, I see a list of graphs by no images

I repeated this procedure a couple times, even on a couple different 
servers, with identical results. I assume that poller.php should create 
RRD files for the default, localhost graphs, in addition to the graphs 
added by me? Or is there another installation step that I'm missing 
where the default, localhost RRD files are created? What's the 
difference between the default, localhost graphs and the graphs added by 
me, such that poller.php creates RRD files for the latter, but not the 
former? Can I provide any more information?

Thanks!

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