approach? create daily window into monthly data: autofilter, named rng, series rewrit

Thanks already. Relatively new to VBA.

So I know two things: 1) I don't understand the charts object model enough or how XL guesses at the src to get the source correctly, and 2) I better get advice to the correct (bestest) way to attack the problem to avoid spinning too much more.

Output desired: daily chart stacked bars, given a day of month
Input: col a/b date/time, col c... about 20 categories
rows about 3000 (15min samples, 96/day)
(its a csv)

I've gotten to point where I can get a day out easily, but have to update the code for day of month. Code then does a select on range and chart.add. All is good.

As soon as I get fancy about selecting a day programmatically, the chart swaps categories (x to y) and sequences a new x. This is true for charts when src is set via autofilter, select, hiding, ....

Back to q2) bestest approach to windowing into monthly data table is? (I didn't post any code as I've tried several variants of techniques...)

q1) reference that explains how XL picks x y when select is A2:AQ2900 (with a bunch of hidden columns in the middle, or how to define a chart and force the x y selection.

I've learned a lot thru this but a pretty vertical curve. Thanks again.