[adi.ptb]

hi guys, i have a problem compiling a udf ,i want to simulate a pulse tube refrigerator,in order to model the piston i used this udf :
#include "udf.h"
#include "dynamesh_tools.h"
DEFINE_CG_MOTION(oscillate,dt,vel,omega,time,dtime )
{
Thread *t;
face_t f; /* define the variables */

t = DT_THREAD(dt); /* get the thread pointer for which the motion is defined */

/* if (!Data_Valid_P())
/* return; /* check if the values of the variables are accessible before you compute the function */

begin_f_loop(f,t) /* loop over each face in the zone to create an array of data */
{
if (time <= 1)
vel[0] = -2* 3.14159 * 2 * 0.025 * cos (2 * 3.14159 * 2 * time); /* define the velocity of the moving zone---*/
else
vel[0] = 0;
}
end_f_loop(f,t)
}
i successfully compiled it,but when i tried to compile this udf for time dependent viscosity :
#include "udf.h"
DEFINE_PROPERTY(helium_viscosity,c,t)
{
real T = C_T(c,t);
return (0.412e-6)*(T**0.68014);
}

it wont compile,i even tried a udf from fluent udf manual:
#include "udf.h"
DEFINE_PROPERTY(cell_viscosity, cell, thread)
{
real mu_lam;
real T = C_T(cell, thread);
if (T > 288.)
mu_lam = 5.5e-3;
else if (T > 286.)
mu_lam = 143.2135 - 0.49725 * T;
else
mu_lam = 1.;
return mu_lam;
}
but it wont compile either,does anyone know what might be the problem?
please help