pooping in kennel at night

Question
MY 18 MTH OLD BLACK LABRADOR KEEPS POOPING THE KENNEL AT NIGHT,SHE HAS TWO OTHER DOGS IN THERE WITH HER.WE TAKE HER OUT AT NIGHT [10.30]AND IM UP AGAIN AT 6AM TO TAKE THEM OUT AGAIN.WHEN I GET TO THE KENNELS SHE HAS ALREADY POOPED.SHE KNOWS THAT SHES DONE WRONG AS SHE BACKS AWAY.WE RESCUED HER FROM A COUPLE WHO USED TO LEAVE THE DOOR OPEN AND SHE COULD COME AND GO AS SHE PLEASED.

Answer
How much exercise does she get when you take her out the last time?  The more exercise, the more likely to have a bowel movement.  You might also consider putting her in a crate by herself to reduce her activity overnight and less likely tto have a bowel movement.  You can try varying when you feed her.  If you aren't feeding a concentrated, meat based food, doing so would help her go longer.