In general, a user defined function (UDF) cannot change any part of the
Excel environment. It can do nothing but return a value to the cell from
which it was called. Normally, attempting to change anything else will cause
the UDF to terminate immediately and return a #VALUE error to the calling
cell. I don't know why setting the Iteration property doesn't cause a #VALUE
error but it doesn't surprise me that you cannot set its value in a UDF.
Functions called from worksheet cells have much more restrictions than code
executed directly.


--
Cordially,
Chip Pearson
Microsoft MVP - Excel, 10 Years
Pearson Software Consulting
www.cpearson.com
(email on the web site)


"Mitch Powell" wrote in message
...
Using Tools, Options, Calculation, I set Iterations to TRUE. When my
user-defined function retrieves the value of Application.Iteration, it is
FALSE, even though I just set it to TRUE using the user interface.

Any idea why?