Report failing after cube rebuild

while building transformer model we always define the unique id and label but most of the time we forget to define the category id's which should not be left for transformer to decide while building the cube. Category id should come from the dimension( database) itself. It will help when cube is rebuild due to any xyz issue as all your exisiting cube based report will keep on working otherwise your exisitng report will start throwing the error as it will search for cognos defined category id's in the cube which is not there anymore due to rebuild of the cube. So always define three minimum things for a level in a dimension id,lable and category id so that life is easy.