I tried to create a chart (a line graph) to visualise my electricity consumption. The system insits on calculating an aggregate figure (e.g. Sum, Avg, Max) for each division on the time axis (e.g. Year, Quarter, Month); I selected Avg and Month. The data I had was just the meter readings on which electricity bills had been based. These readings were somewhat irregular w.r.t. timing but this was not reflected in the graph, the data points being evenly distrbuted along the time axis, one point per month. This distorted the picture somewhat but much worse was the fact that if no reading had been recorded in a particular month (and there was one instance of there being no reading for two consecutive months) then that month was just omitted. This seems a very strange and highly unsatisfactory way to behave. Has anyone had the same experience.