Hi Brian,
If you can upload the model, I will take a look at it on Tuesday morning, and if you don't already have the problem resolved by then. I will be away from my office on Sunday and Monday is a Federal holiday for us. In the mean time, you could upload some images of your model with the entire model tree expanded (with nothing hidden or suppressed). If you're getting that message, then you have something already named "A" somewhere in your model.