Did you really push the button "Add New Attribute"? Otherwise the entry does not work.
well I'm working in NX7.5, so I don't have this command button. You're working with a higher version of Siemens NX.
All available options are illustrated in my images.
after some trial and error, now it's working properly.
When I choose Edit > CAM Component type
I first have to select my target component in the graphics window, then specify as "Target" from the pulldown menu, thereafter clicking "OK".
Now, when I look at the properties of the target component, it has the CAM Component type "Target".