c - UDF not appearing in Ansys Fluent

Question

I'm trying to prescribe simple motion in 2D, from right to left, at a constant velocity without the effect of gravity.

The code (shown below) was typed up in notepad and saved as a .c file which was then saved to C:\Programs\ANSYS19R3\v195\fluent\ntbin\win64. For some reason it's not appearing in the motion/UDF drop down box after being selected. This is my first time using C.

The code:

#include "udf.h"

static real velx = 0.0;

DEFINE_CG_MOTION(airfoil,dt,velocity,dtime)
{
    NV_S(velocity, =, 0.0);

    velx = -75;
    velocity[0] = velx;
}

Thanks in advance!