I have one list box with payment months (structure is YYYYMM), and then I have a bar chart diagram (SalesTable) showing the sales for the last 13 months.
What I want to set up is as below
1. I want to find the lowest payment month of the selected months in the list box
2. If the lowest month is >= the last 13 months the SalesTable should only show the selected months
3. If the lowest month is < the last 13 months the SalesTable should only show a error message
4. If no months is selected in the list box the SalesTable should show the default 13 last months sales