[Closed] custom_attributes_presets mxs code … 'dll not found'

I have a line of mxs code which adds the presets modifier to a ca,(using custAttributes.add <obj> CustomAttributesPresets) , which works fine for the session, but after saving and reloading the associated file I get a ‘dll not found’ message (scripted plugin custom attributes presets, superclass :0X1160)…do I need to find the dll and place in start up folder or plugin folder or…what?