incorrect grid motion UDF deforming on zone ??????
 

HI
I want to deforming thickness variations of the pressure plate(6x50x200mm) in each cell(deform Cells of the upper face plate):
y=0.2601*exp(-6.147e-X*0.5) + 0.5091*exp(X*(-0.0007079))
(X=pressure , Y= thickness variation).

for this purpose i writed below udf but mesh Error:

************************************************** **********/
#include "udf.h"
#include "mem.h"
DEFINE_GEOM(deforming,domain,dt,position)
{
cell_t c;
Thread *t;
begin_c_loop_all(c,t)
{
position[2] = position[2]+ 0.2601*exp(C_P(c,t)*(-0.00006147)) + 0.5091*exp(C_P(c,t)*(-0.0007079));
}
end_c_loop_all(c,t)
return;
}

Error: Warning: incorrect grid motion UDF deforming on zone 59 (assuming no motion)

can anyone help me in regarding with above problem….
thanks