There is a unit/base unit relationship that is not valid in this unit group. This base unit cannot be selected until the ...

There is a unit/base unit relationship that is not valid in this unit group. This base unit cannot be selected until the relationship is fixed. Review the other units and fix any looping conflicts that exist. For example, a loop is created if Unit A is specified as the base unit for Unit B, and Unit B is specified as the base unit for Unit A.