Hi.
I am not sure about your question.But,
1) are you sure that you activate the depreciation key?
? And you verify that you set for the correct Chart of dep?. (is a comon issue).
2) In my case, i have two differents experiences. (i did not have the period field in my cases). So, how i worked. Depends on the clients requirements i used.
2.1 ) Modify the asset , and replace for the new depreciation key (with one calculation key with the new criteria) at the asset level, and then run the AAVN (recalculation option). Depends on the criteria, of the calculation key, the values of the asset can vary from the beginning, or not.
2.1) Modify the asset, and replace for a new depreciation key with two two calculation key, similar to the follow image (the one´s that already used for the asset, and the new one).
In this case, we have a depreciation key with an specific calculation key (base method). and through the change method, i gave a criteria to take the new "base method" for the depreciation.
3) About level screen. For the Year column all time i used 999 or an specific number but i never use 0 (and depends on the case, i need to analyse if i use or not the remain life flag).. Also, you will need to pay attention about the the validity start field.
4) i have an additional observation. For reporting and classification of the depreciation is good to assign a class.
Regards, Viviana