Make sure the brake hose is not kinked as it exits the hard line from the car.
Some people let the calipers hang which kinks the hose then they don't pull the hose back up through the grommet on the strut and it stays kinked so that when you press on the pedal the brake pressure doesn't distribute evenly between the two calipers. It's easily overlooked.
If this isn't he isue and you've check the slide pins and they are clean, lubed and slide freely, and the spring is installed correctly then you may have a bad caliper.
