I agree with what everyone else has said, but I want to add that maybe YOU are not cueing her correctly as the rider.
When you test rode her, you were riding her in a familiar environment. I bet she could run the barrels in her own home practice pen with her eyes blindfolded with no rider.
It's a different ball game when you've hauled her to her new home, and she truly hasn't done the barrels in a long time (as her previous owner did say).
And you as the rider are completely new to her. It's going to take time for the both of you to get used to each other, and for you to learn what the best way is to cue her. If she doesn't know what you do, you need to help her understand. So no big deal that your first practice session didn't turn out with a smokin' 1D run. It's going to take some TIME and PATIENCE.
∞•*˚ Βгįťţαňγ ˚*•∞
It is not enough to know how to ride; one must know how to fall.