SAP Message C1828 - Inheritance data prevents selection for "&"

Diagnosis
You are classifying an object and want to assign values to acharacteristic. However, inheritance data prevents you from doing this.

System Response
The system checks whether the object is classified with more than oneclass. If it is, the system checks whether the same characteristic isused in more than one of these classes. If the characteristic hasdifferent values assigned to it in two different class hierarchies, andthe class with which you want to classify your object inherits thevalues, you cannot assign a value to the characteristic. The objectmust have the same value in both classes. However, in this case theobject would have two different values for the same characteristic, sono value is assigned to the characteristic.