Ensure you do not have old configs at place when re-installing packages. If there is glitch in config, new package will use it and you will end up in very same situation. (i have just one empty option line in “df” plugin, or in ‘ping’ empty hostname… which kind of prevent collect/rrd to work properly). When restarting rrdtool be sure you have no old rrd files at place.
There is similar thread about statistics Where are statistics graphs?