SAP Message 1E216 - Conversion date being changed from &1 to &2

Diagnosis
You entered conversion date &v1&.
For the bank area it was defined that the conversion date must beexactly one day after an account balancing.

System Response
The system changes the conversion date to &v2&. This date is exactlyone day after the account balancing nearest to the date you entered.

Procedure
Accept the date or enter another date, provided this date is also oneday after an account balancing.
You can also first change the date of the next account balancing andthen re-enter a conversion date.