You can also make the graphs by hand. Something like this should give you a PNG file you can load in your browser. Tweak the graph settings until it looks right, then update the graphs.cfg for Xymon.
NOW=`date +%s`
START=`expr $NOW - 604800 - 604800` # this sets the start to NOW-14 days
UPDATE=`date +'%F %T' | sed -e 's/:/\\\:/g'`
RRD=/var/lib/xymon/rrd/somehostname/something.rrd
rrdtool graph /var/www/html/somehostname.png \
"DEF:thing=$RRD:thingvariable:AVERAGE" \
"LINE2:thing#$COLOR:Total Thing Status" \
"GPRINT:thing:LAST:\: %5.1lf %s (cur)" \
"GPRINT:thing:MAX: %5.1lf %s (max)" \
"GPRINT:thing:MIN: %5.1lf %s (min)" \
"GPRINT:thing:AVERAGE: %5.1lf %s (avg)\n" \
"COMMENT: Updated\: $UPDATE\n" \
--title "Thing Status - 14 days" \
--vertical-label "Thing" \
--width 864 \
--height 120 \
--start $START \
--end $NOW
Ralph Mitchell