Flat amount DBA not calc

We need to set up a Flat amount DBA (Benefit) for employees that every pay period, they will earn as retirement fund 200$. We set it up as Flat amount but it is not giving the flat amount of 200$ per pay period but it appears to be calculating from something. There should not be a basis of calc but since the system requires it, we put pay types 1-999. How should we set it up so automatically, employees under this plan will get 200$ per pay period.