Hi Stephen,

As I was playing around with the spreadsheet this weekend, I kept noticing that whenever the data table values are recalculated in the worksheet, the calculation method changes from 'automatic except data tables' to 'automatic'. Could it possibly be due to 

.Calculation = xlCalculationAutomatic
being part of the code? To see this error, try checking the calculation method in the worksheet and then change values in the optimisation table and hit the 'update' button. When you do this, see if you get the workbook recalculating. It would be fine, but the actual workbook I have is very large and this recalculation takes a very long time and slows down the workbook.

Also, as the axes were mixed up, I tried switching the row and column in the code you provided but it gave me a invalid parameter issue.

Could you please advise on how I would switch the axes based on your latest code?

Thanks,

Maani