3602154 - Remaining balance from previous years is not getting calculated when create new time account even if rule is configured

The business requirement is to:

Create annual leave for each year requires calculating the remaining annual leave from previous years

But after execution of Accrual rule, it can be found: 

Accrual Rule Variables.Balance is retrieved as NULL.

(Rule log: Retrieved 'accrualRuleVariables.balance'. Value: 'null'.)

The balance needs to be the sum of remaining annual leave from previous years.

SAP SuccessFactors Employee Central 

Variable is not defined at the beginning of the rule for balance.

1. Firstly define variable for balance according to Handbook: Implementing Time Management in SAP SuccessFactors >> Using Variables to Store Interim Rule Results.
2. Then use variable in rule configuration. 

Variable, Accrual rule, Time off, Beginning of the rule, Sum , KBA , LOD-SF-EC-TIM-JOB , Time Management in Job Info - Records & Objects , How To