If the HOUGAARD option is specified in the PROC NLIN statement and there is an active BOUND involving more than one parameter, both Hougaard's measure of skewness and the standard errors of the parameters will be incorrect.

To circumvent the problem with the standard errors of the parameters, remove the HOUGAARD option from the PROC NLIN statement. There is no circumvention for the problem with Hougaard's measure of skewness.