An early goal by Lee Hughes and one in each half for winger Ashley Vincent saw off the Dons, and Ardley was quick to admit he got his tactics wrong.
He said: "I'll take the rap because I took a calculated risk by playing five at the back and it didn't work.
"Vale's front four are the most potent in the league, their record tells you that, and I thought the best way to combat them was to change our tactics.
"It's a big pitch and I went for pace up front with Rashid Yussuff, but we soon gave a poor goal away from a set piece and it was a very difficult night after that.
"Vale are a very good side and they played a lot better than us. There weren't really any positives to take from the game, but we've got to draw a line under it and move on.
"There wasn't a lot of belief, but I've got a lot of good characters in the dressing room and I'm confident we can bounce back and be all right."