Wiring issues, illuminated switch?

Ok, so I wired up a temporary solution for a cargo/hunting light. I stole two lights, brackets and harnesses from a junk cotton picker we own, so they are fairly bright and the mounting is solid. Running a hot wire from the engine bay into the cab, through the firewall and hiding it well isn't easy BTW.

Anyway, my question only has to do with my switch. I bought an illuminated switch from radio shack, which only has 3 posts.. And it won't illuminate at all. So I used the illuminated black rocker switch from the cotton picker. By ohming it I found which posts were hot posts. It has 4 total posts, though, and while it works for turning the lights on, I still can't get it to light up when the lights are on.

I really don't care, I know when, it's on and when it's off, but now it's a matter of principle. Can anyone help?