Changeover methods

Hi all,

I am tryng to create a changeover method by adding functionality in user exit EXIT_SAPLAFAR_003.

However there are a lot of unclearities regarding how that is done.

I can't even debug the user exit. I coded in a break point in function module, but when I run transaction AFAB nothing happens, allthough depriciation is performed for several asset items. When is depriciation performed and when does changeover method come in play? Do I need to run some other transaction or does the asset item data need to be prepared a certain way for the changeover method to come in play?

Thanks in advance for all the helpful answers!

BR,

Armin