[Xymon] month graps

[Steffan]

Hello,

I have my values in mysql
the values are every 15 minutes generated.

Im now using this
/usr/bin/rrdtool graph '.$filename.' --step 900 --imgformat=PNG --title "'.$title.'" --slope-mode  --vertical-label="Wh" --alt-autoscale-max --start='.$start.' --end=+1hours --width=600 --height=300 "DEF:min='.$DS_BASE.':min:AVERAGE" "AREA:min#00FF00:Opbrengst" GPRINT:min:LAST:" Current\:%8.2lf %sW"  GPRINT:min:AVERAGE:"Average\:%8.2lf %sW" GPRINT:min:MAX:"Maximum\:%8.2lf %sW\n"	

The problem that I have is that the older values (month graph) has lower values ( I think average)
Is there a way to prevent this is happening?


Steffan