Try using the 'Apply Object Transform' option, which sometimes artificially skews the transformation. This will reset the original object transforms, which may not be what you wish. If you are still having problems, don't hesitate to contact me through the Blender Market website.
The add-on should work on selected objects or curves, but not specialist objects like metaballs which do not have a lattice option. If you are having any problems, contact me through the Blender Market website.
This add-on works on selected meshes or curves. If the menu item does not appear, it may be that you have selected something that cannot be deformed, such as a camera.