Diagnosis
You have made an entry in the Amount from field. However, thereis no entry for Amount from = 0 for this interestcalculation rule, currency, debit/credit indicator and date. Thisrecord is absolutely essential.

Procedure
First maintain a record where Amount from = 0 for thisinterest calculation rule, currency, debit/credit indicator and date.Only when this has been done will you be able to save the record.