error is Value exceeds open accruals 0,00

Expetr

While Setting the rebates: For partial settlement I follwed the below steps

1.VB02

2.Entered rebate agreement number 99

3.Change agreement status field as B

4,.Choose create manual accruals and enter the amount to be paid 50

The error is Value exceeds open accruals 0,00

Help to solve the issue

Regards