Diagnosis
You want to determine the option rate on the basis of the settlementfactor. However the settlement factor for the service charge settlementspecifies distribution according to consumption, or at least twoapportionment units are valid and the share of each has to be takeninto account.
In both cases, you have to specify a different settlement factor todetermine the option rate.

Procedure
Either enter a settlement factor for option rate determination orchange the calculation base.