UDF charge density in mhd model dpm
 

I want to use the charge density of the inert particles with udf when I turn on the mhd model and use dpm.
However, when using discrete phase sample on reports, it caused an error even writing code that only takes very simple constants.

Error at Node 2: get_udf_function: function charge_density :: abc has wrong type: 2! = 43

I wonder what kind of type requires and what the wrong type means.
If anyone has applied udf to charge density, please help.

P.S. code is very simple

#include "udf.h"
DEFINE_DPM_PROPERTY(charge_density,c,t,p,i)
{
return 5;
}

Thanks for read my post. :)