my story has some relevance which may help.
when i installed a small neon to light up a lil sign in my car, i hooked it up to my head unit(pioneer DVD player) wiring. either the neon or head unit would work, not both. i put this down to too much power being robbed from that specific source. also when the fuse blows for head unit, the clock goes off aswell so they must run on the same source.
i wired my boost gauge up to the cigarette lighter light and it works fine. try this and let us know how it goes