FF "Dependent Coverage Start Date"

I am working with unrestricted events, as the employee can enroll and disenroll from a plan at any time.

I created a formula of the type "Dependent Coverage Start Date." This formula has a simple logic to return the Date of Birth of the dependent being enrolled as their Coverage Start Date. (Later I will add more complex logic)

The formula was successfully compiled.In self-service, when clicking on "Enroll in benefits that matter to you," the error message below is displayed:

Below are screenshots of the settings and FF code:Plan Configuration Screenshot

Plan Configuration Screenshot

Formula compiled successfully