Problem called : thumbnail views fail when using empty COMMENTs
Problem display from : /var/log/httpd/error_log
Type error : ERROR: Expected some arguments after ‘COMMENT:’
Detected from system :
Linux Fedora release 7 (Moonshine)
rrdtool-1.2.27-1
cacti 0.8.6j
Solution :
patching file rrd.php in folder <your_cacti_folder>/lib/rrd.php
with this patch rrd.php
or from original cacti.net

