JClass- Zoom action of JCChart3d (55197)

I created the text field to allow a user to enter a number for zoom action. When the user enters the number, I will then change the zoom value:
JCChart3d.getChart3dArea().getViewport().setScale(<number>);

After changing the scale, the result is not what I expected. It looks like it's just doing the scale, but not doing zoom   value. Is this enough for setting the zoom value? what else do I need to do?

Please review the following documentation: In <JCLASS_6.4.2_HOME> docs/api/com/klg/jclass/chart3d/JCViewport.html#setScale(double)
public void setScale(double scale)

Sets the zoom factor. A value less than one means a viewport smaller than the default. A value greater than one means a viewport greater than the default (the graph image will be clipped by the JCChart3dArea).

Parameters:
scale - the new scale zoom factor

JClass is behaving as expected.