I think I am looking for the same effect.
I have a grid with values in it; quantity, price, discount (%), unit price.
If the user wished to place a discount on each row, they enter it once, and then in a For Each loop, I place the value in the cell; however the calculation does not take place. it appears as if the CellValidating or RowValidating events are not firing.
Here is my snipit of code:
).Value = DiscountTextBox.Value
The user can manually enter a value in the discount field, and the calculation takes place.