error "P_POS: undeclared variable"
 

Hi
I'm trying to write a UDF for body force appling on a particle. the body force is dependent on the position of the particle, so I used P_POS(p)[i] macro for this purpose. But after interpreting the UDF in fluent, there's always an error entitled "P_POS: undeclared variable". however this macro is mentioned in the FLUENT UDF manual. would you help me?

thanks,

Complex UDFs should be compiled.