Assign posting periods to authorization group in tcode S_ARL_87003642

Hello,

I want to restrict posting periods for some users. Therefore, I have created 2 functions associated to 2 authorization groups.

In transaction S_ARL_87003642, when I try to assign different posting periods to each authorization group to the same company code (Posting Period Variant) it appears a message saying u2018Target key must be different from source keyu2019.

What am I doing wrong? Do you know how can I restrict posting periods for some users?

Thanks and regards

Ana Rita