1988 cherkoee cigarette lighter issues

ok, granted i'm not real smart on how the lighter itself works, but
here's the story...

my cigarette lighter works - i push it in, it heats up, i can light a
cigarette with it.

however, my xm power adapter for the new roady i just picked up does
not work.  the adapter itself is good, i know this because i've tested
it in another vehicle...

why would the ligher itself work, but not be able to power anything
else?