Why can't I add a Jounal Entry Rule Set Assignment in Accounting Method?

I want to add a new Jounal Entry Rule Set Assignment in Accounting Method.

To do so, I entered the Effective End Date of the seed Jounal Entry Rule Set Assignment and entered consecutive dates in the Effective Start Date of the new Rule Set.

When I tried to register in this state, the attached error occurred.

All assigned Subledger Journal Entry Rule Sets are active.

Please let me know if you know the cause and how to fix it.

Thanks,

Mayuko