Hi,

I have 11 WBs structured exactly the same way.
Every WB contains 30 WSs, the WSs Tab names are the same for every WB.

Now the problem:

One WS (Sheet1) gives results performing a calculation that involves another
WS (Sheet2).
Below is a typical formula in a cell

=IF(ISERROR(I45*'Sheet2'!I47/1000),0,I45*'Sheet2'!I47/1000)

Everything works fine if in 'Sheet2'!I47 there's a value.
But if there's no value, obviously what I get in the WS (Sheet1) is an empty
cell.
Mathematically is correct, but what I need instead is the following:
If there's no value, then I want the cell in Sheet1 to pick up another value
in another WS (Sheet3).
Basically the instruction should be:
If you don't find any value in 'Sheet2'!I47 then put the value that you can
find in Sheet3!A1

Probably I can do this in two ways:

1) Changing the worksheet formula, but I don't know how.
2) Programmatically (also no idea how)

Thats where I need your advise, since I discovered this problem by chance, I
really don't know if this happens somewhere else in the other WSs and where.
Therefore, I need something that I can apply to all my WBs and automatically
apply the new formula were it is needed.

I hope this is clear enough and allows you to give me a good solution.

Thank you!
Alex