This is really strange, I have tried your latest code and it works, when I pick a day from the list box the chart updates to the correct day. However if I manually set the day in code. ie change your code to ..
(startDate.DayOfWeek != DayOfWeek.Thursday) startDate = startDate.AddDays(-1);
//while (startDate.DayOfWeek != ReferenceDay) startDate = startDate.AddDays(-1);
.chartProcessHistory.DefaultView.ChartArea.AxisX.MinValue = startDate.ToOADate();
.chartProcessHistory.DefaultView.ChartArea.AxisX.MaxValue = DateTime.Now.AddDays(3).ToOADate();
It stops working and goes back to the results in my post above (no matter what day I pick the chart starts on a Friday)… ?
Does it happen for you if you hard code the day rather than use the dynamic list box ?
I have tried displaying a message box of the computed startDate after the while loop and it correctly displays the startDate as a mon, tue, wed etc.
Thanks for your time on this, I'm really confused.