How to retrieve the vector value of a specific vertex at a certain point on the timeline?

var target_vertex_index = 21616;
var frame_range = [0, 4];
var time_step = Scene.getTimeStep().valueOf();
var start_time = frame_range[0] * time_step;
var end_time = frame_range[1] * time_step;

var geometry = Scene.getPrimarySelection().getObject().getCurrentShape().getGeometry();

for (var i = start_time; i <= end_time; i += time_step) {
	Scene.setTime(i);
	var target_vector = geometry.getVertex(target_vertex_index);
	print('[%1] target_vector: %2'.arg(i).arg(target_vector));
}

I ran the script above to observe the change in the vector value for a fixed vertex index on a character with animation applied.

However, the result outputs the same value.

Is there a way to properly retrieve the vector value of a specific vertex as time progresses?

Thanks in advance.