We know that all beer bottles aren't the same height. So in an effort to accommodate as many bottles as possible, we designed the lid to have a height range. So your BottleKeeper lid may not tighten all the way with certain bottles but is absolutely working as intended -- meaning the custom seal is connecting with the beer bottle and keeping the beer, well, in the beer bottle. Many beers will have the BottleKeeper cap half way up or so but I assure you that it's working exactly as intended and your beer is definitely one of the 'great fits' on our list.
When inserting the beer bottle, make sure you take the lid off, insert the bottle and screw on the base, then push the beer bottle as far down toward the base as possible -- screw on the lid as far as it will go and you're all set!