This may semm easy to a lot of you, but here goes...

I have created macros that transfer data from a list format into 15 cost
centre spreadsheets linked to a total sheet for each accounting period (AP)
of the year.

I have created a form at the front of the workbook so that the user can
select a button relating to the month that they wish to populate data for.
When they click a button, the macro enters (hard code) the corresponding AP
number into a cell on the total sheet to format all sheets from forecast to
actual data.

I want to use Data Validation to prompt the user to confirm their selection
so that after they have selected the AP they wish to run, a warning message
is displayed asking them if they wish to continue before the data upload
takes place. However, data entered by the macros into the cell I wish to
validate does not cause the error message to be displayed.

Does anyone have a solution please...?