How can I have the Plan Period Start Date in the Vacation Plan taking the Benefits Service Date?

Hello All:

I configure my vacation plan for Mexico, where the Plan Term is:

Type: Anniversary year

Anniversary Event Rule: Adjusted service date

The plan has a repeating time period monthly and contains a Fast Formula with the amount of days the employee should get or acumulate on their anniversary.

Once the employee gets the anniversary date the Vacation Plan Rolls over the days employee acumulated to another Carryover Plan that is linked, since the requirement for Mexico is 18 months of Carryover Expiration and the system allows only 12 months in the configuration.

The Issue I am having is that the vacation plan should take the Benefits Service Date to calculate accruals and seniority and seems like it is not doing it: