I've tried to put data validation on a cell that gets its value from another
cell, in another worksheet. When the value changes, data validation does'n
kick in. How come?
This is my example: cell A1 in sheet2 is equal to B2 in sheet1, I put data
validation on cell A1 in sheet2. When the value in B2 sheet1 changes, it also
changes in A1 sheet2 but the my validation is not followed and no pop up box
appears.

Any info would be helpful, thanks!