You may want to review JE McGimpsey's notes:
http://mcgimpsey.com/excel/udfs/sequentialnums.html

Personally, I wouldn't use the changing of a cell to grab a new number. I'd put
a button from the forms toolbar on the worksheet and force the user to click the
button when they wanted it.

Anything else would seem too much like magic <vbg.

Heather C wrote:

I need some help writing a macro in visual basic. I'm tring to give an
invoice number to each new invoice. I don't want it to do it every time I
open the program though, I would like it to be done when I enter the customer
number into the field. I'm not quite sure how to do this.

Please Help!!

--

Dave Peterson