I recently bought a KBOX and a Subtank mini. I love it but I'm having a problem when I put the tank onto the box. It has done it since I bought it and I'm wondering if I need to take it back and get it replaced or maybe it's normal. Every time I screw the tank on, if I put it on all the way so its tight it engages without even pushing the button. As long as I don't screw the tank on tight it's fine, it still works just fine. It's like it has a sweet spot and if I tighten it past that spot it engages. Suggestions? Please? It's driving me crazy! Thanks in advance!!