interpret or compile
 

I would like to define the user-defined mixing law. The UDF is as below which is UDF provided by UDF manual:

#include "udf.h"
DEFINE_PROPERTY(mass_wtd_k,c,t)
{
real sum = 0.; int i;
Material *sp;
real ktc;
Property *prop;
mixture_species_loop(THREAD_MATERIAL(t),sp,i)
{
prop = (MATERIAL_PROPERTY(sp));
ktc = generic_property(c,t,prop,PROP_ktc,C_T(c,t));
sum += C_YI(c,t,i)*ktc;
}
return sum;
}

Once I interpret the file, error message appears as below:

structure reference not implemented

Somebody please help me to solve my problem. Is compilation should be used instead of interpretation? Or any other appropriate solution for it?

Thanks for help.

Best regards