Picture of black area
(http://)(http://i246.photobucket.com/albums/gg110/lumpysphotos/black002.jpg)
Lumpy
Limpy I would conquere of what others said about smoke condensation. I have had this happen to me with some chickens before.
HR
I agree with HR, it also has happened to me as well with some jerky and a butt roast. I think my problem was that it was cold outside and I left the vent closed to much, causing to much moisture around the vent. So the excess water would drip down on the food. Hope this helps. :)
Looks like the black nasties have dripped on your sticks. Wipe the inside of the vent off and run vent wide open if you don't already.