Directions were hard to follow. I could not figure out how to make the bag air tight at the zipper at first, and my initial conclusion was that the system did not work. I searched for an alternative system and then saw that other systems had locks on the zipper. I looked at your system and then realized how the locking mechanism was meant to work. When I gave it a second try, I figured it out, and the system worked well. But you might make that bit clearer for the uninitiated and/or those wh...