how to default element value using compensation default and overrride

while changing salary of employee we want to give a default value for one component using fast formula conditions.

But it's not working. we are attaching fast formula at element default validation section with formula type as default and override type.

Is there any alternative way to default a value of component (element) using fast formula in compensation.

while we are trying to attach the formula at default value section the formula is not showing.