Rear brake noise

I just replaced the rear pads and rotors on my 1998 GP GT and when I apply the brake, I am getting a grinding noise from the driver's side. Is it possible that I installed the pads incorrectly? I have the pad with the wear sensor on the outside and replaced the metal clips that were included with the pads. I also coated the back of the pads with the lube supplied.
Any ideas?

What year vehicle?

Actual date when replaced?

What type of pad used? Semi-metallic? Ceramic?

Notice any rusting of the rotors on the outside/inside contact surfaces?

Did the sliding pins move freely?

It's a 1998 GP GT and the pads were replaced last Thursday. I think I may have missed a step as I did not remove the sliding pins (actually my neighbor who was helping me). There was no rust and I cleaned the area before reinstalling. The pads are ceramic. I have read many posts on installing pads but they all seem to be for the front. Is the procedure the same for front and rear? I read a post for this procedure in this forum complete with diagrams but I can't find it again. Maybe you can point me to the post.
Thank you.