There's a lot of missing details to your complaint to really tell if something actually happened. What npc level was it? What troops did you use? What was your hero's attack value? What level was the enemy hero? What were past successful battles like? Are you sure there weren't any differences between past battles and the last one?

EDIT: I posted at the same time as your last post. The battle reports would explain most of my questions.

PS, here are a pair of perky boobs for you: