Did you put the whole pack into the "Sights" folder? I mean, do you have another folder inside the Sights? I don't know about Buster's pack, but at least some other packs, both sounds and sights, have been made by zip packing the author's own "Sights" (or "Sounds", for that matter) folder. In such case the zip pack shouldn't be unzipped to the target folder. Instead it should be unzipped directly to the AcesHigh folder where it should replace the previously existing one unless there either hasn't been one yet (fresh install) or the previous one has already been renamed for backup purposes.
If you have double Sights folders one inside the other, just cut the files of the subfolder and paste them to the Sights root folder.