changevalue and newvalue

Newvalue is triggered when a new value is entered into a field but is also 
called on opening.
I have a rather large database which has similar fields (we will call them

ASA1 and ASA2) in separate, but linked tables. The fields are not
identical 
for good reasons which I will not discuss here.
However, when one of those fields changes, I want to take the value of the

field, perform an operation on the value and then put the new value in the

other field.
The code for that part is easy, but it runs upon opening as well as a 
newvalue.
Changevalue doesn't seem to work all the time. It will work if move off
the 
field by hitting the tab or enter keys or use the mouse to touch another 
field. This form is a notebook and if I click on the a new tab to look at 
the other field, the other field has not changed.

Since CanDeaprt fires before changevalue, I tried putting
self.postrecord() 
in that but, it didn't seem to help. I am sure the Real Programmers out 
there have dealt with this many times before and there is a relatively
easy 
answer.

As always,
Thanks for your help ahead of time.

Craig Futterman