PROC CAPABILITY will abnormally terminate when the CLASS= option is specified on a COMPHISTOGRAM statement, an INSET statement is specified and specification limits are provided either in a SPEC= data set or on a SPEC statement and one or more CLASS levels have exactly 4 nonmissing observations. The procedure will an issue error message such as a domain error or invalid operation.

To circumvent this problem, use a HISTOGRAM statement instead of a COMPHISTOGRAM statement and specify the CLASS variable(s) on a BY statement.