I am trying to allow users to plot data for different products on a
single chart. The macro calculates the data ranges and then assigns
the XValues and Values to the appropriate series of the chart by
overwriting the previously assigned series values. Sometimes the macro
works perfectly and the chart is updated; sometimes I get run-time
error 1004: "Unable to set the XValues property of the series class".

I've checked; the selected data range is correct for each product and
the format of the series value that I am trying to assign is
consistent and is in RC format.

Could anyone give me a hint as to what is happening and how to fix
this?

Regards, Alan