Function result differs between single execution and series of calls.

[jul_thi]

I have a function that creates a chart in Excel. When executed/called alone the function's result is as intended.

It takes two regions Range("A3:A4") which are the titles and unites them with a second Region("F3:F4") which are the values.
With a little automated formatting, I end up with pie chart of two pieces and a legend with two entries.

When called in series of other functions. I end up with a chart that has the correct Regions as Source selected, but the Pie has only the upper Series selected. Why is that? What did I do wrong?

 

[jul_thi]

Okay. I found out that if I do

Chart.PlotBy = xlRows

in a single call, I end up with the correct result.
But not so in a series of calls. There I have to

Chart.PlotBy = xlColumns

for a correct result or I will end up with an error for a missing series.

How does this make any sense at all? Is this a mistake on my part or is VBA just inconsistent?